Based on review comments, revert the isHistogramData method to its
original form without any parameters to avoid encouraging creation
of matrix workspaces containing histograms with mix of xModes
Create private function instead that allows a specific histogram to
be checked

The unit test suite MonteCarloAbsorptionTest has occasionally been failing
with an access violation on Jenkins. I've been able to track this down to
the test Lambda_StepSize_Two_Linear_Interpolation which was failing

I can reproduce this locally by modifying the test to repeat 1000 times
and it eventually fails. Although the access violation occurs in a couple
of different places:
a) the y() or e() vector in the 0th histogram is sometimes empty once the
MonteCarloAbsorption algorithm completes which causes some of the test asserts
to fall over because they assume y(0).front() or e(0).front
b) sometimes the code in MonteCarloAbsorption itself has an access violation
when yIndexOfX returns an index out of range of the histogram

Both problems happen in the multi-threaded code in MonteCarloAbsorption and
it seems to be the interaction between the call to MatrixWorkspace::yIndexOfX
and the code that updates a histogram with interpolated results via
MatrixWorkspace::setHistogram. Something in these two functions isn't threadsafe
I found that yIndexOfX calls IsHistogramData() which checks the 0th
histogram in the workspcae even if the MonteCarloAbsorption code is
processing the 1st, 2nd etc workspace
I think if the 0th histogram is in the process of being updated by another
thread then yIndexOfX can fail or else the setHistogram call fails.
I have done two changes:
- only call yIndexOfX once (there was a redundant 2nd call)
- I have modified yIndexOfX so it takes an additional histogram index parameter.
This allows me to keep each MonteCarloAbsorption thread interacting with a
single histogram only. I have defaulted the new parameter to zero so other
code behaves as before

Giovanni Di Siena authored Mar 31, 2020 and Gigg, Martyn Anthony committed Apr 07, 2020

In places other substitutions have been made, e.g
Clang does not yet specialize std::shared_ptr for T[]. Vector
has been used instead. The operator[] methods were incorrectly
marked const but returning a non-const reference - this has been fixed.
Refs #25842

Also updated class_maker.py

This commit replaces all header guards in DataObjects with #pragma once

This is based on the prototype derived from the meeting at the DMSC last December.

The workflow is as follows:
  - Pool all events received from the Kafka stream into a single buffer
  - When the buffer is to be flushed (i.e. events populated in the EventWorkspace):
    - Parallel sort the event buffer by the detector ID/workspace index
    - Determine group boundaries
    - Parallel insert events into EventWorkspace

Also included is the optimisation of using a spec to ID mapping based on
a vector rather than map.
This provides better performance during the initial event buffering
(where this lookup is made).

Initial benchamrking shows 25M events is a intermediate buffer threshold
for LOKI (9 banks) at 10^7 events per second.
This manages to maintain well over 14Hz pulse rate (with no post
processing).

A new pure virtual method getSpectrumWithoutInvalidation() was added to
MatrixWorkspace to enable calls to mutableY() and similar without
invalidating the common bins flag.

Re #24292

Update copyright headers in all files

Squashed commit of the following:

* First version of a script to manage copyright statements

re #23468

* Neatened up script, added comments

re #23488

* move script to tools directory

re #23488

* small script changes and a couple of manual file changes

re #23488

* Minor chnage to whitespace detection in regex

re #23488

* Add an excluded directory

re #23488

* remove a repeasted copyright statement in a file

re #23488

* Don't comsume the comment end if it is on the same line

re #23488

* fix error in new copright parsing

re #23488

* remove double copyrifght entry

re #23488

* Improve handling of old copyrights at the start of comments

re #23488

* remove empty comments re #23488

* exclude gsoapgenerated directories

re #23488

* Sort out greedy line matching re #23488

* improve empty comment removal

re #23488

* improve false positives

re #23488

* impressive speedup by limiting regex matching length

re #23488

* remove evil invisible non ascii character

Also upadte the copyright at the same time

re #23488

* resolve multiple copyrights in a single file

re #23488

* resolve an issue with new statement detection

re #23488

* another unprintable unicode character

re #23488

* pep updates and cmake the new copyright fit clang format

re #23488

* update already done new format headers

re #23488

* wrong type of bracket

re #23488

* Update class_maker and friends

re #23488

* Update all copyright statements

re #23488

* clang format re #23488

* flake8 warnings re #23488

* Flake8 warnings re #23488

* Exclude .cmake.in and rb.in files

re #23488

* replace missing line re #23488

* exclude .py.in files as they are flasely recognized as C++

re #23488

* another setp.py.in re #23488

* another .py.in correction re #23488

* Hopefully the last of the .py.in files re #23488

* resolve utf-8 encoding of python files and changed ABINS checksum

re #23488

* updates to unit tests that reference line numbers

re #23488

* remaining unit test files and other fixes

re #23488

Update to clang-format-5 and reformat the codebase 

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
#
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.

Merge to ensure CrystalFieldFunction is available and up to date.

Conflicts:
	Framework/API/inc/MantidAPI/MatrixWorkspace.h

Also removed misleading comments about clearing MRUs. Clearing MRU not
necessary for Dx, and cleared automatically by EventList::dataX.