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

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 

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Merge done to enable documentation be be fixed, because of removal of
alias directive and addition of related algorithms directive.

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>

re #21243

re #13925

with CopyPropertiesfrom

re #13925

Refs #8784

to algorithm base classes.
Refs #4218

Touches nearly everything unfortunately but is necessary.

To fix SANS system tests

This should have it now

Oh, and I changed the default separator of multiple categories to ; rather than ,

Forgot the IAlgorithm and AlgorithmProxy changes - included now

Added tests for correct alias.
refs #2823

This should be everything I need for the Framework to make using the Load algorithm much simpler (including from C++). Re #2329

Rename Framework code directory to just that. Also delete Main and VS & Eclipse project file. Re #1881.

Refs #1455: on Linux, at least, qtiplot build raises many many warnings when a function returns a const int; changed Algorithm's version() function to return just an int. These raise 'type qualifiers ignored on function return type' because the const on the return value is superfluous, according to: http://stackoverflow.com/questions/1134237/pedantic-gcc-warning-type-qualifiers-on-function-return-type 

Modify AlgorithmProxy::executeAsyncImpl to avoid creation of third, redundant thread when executing algorithms asynchronously (e.g. in MantidPlot). Also some tidying up of the affected files. Re #1333.

LoadNexus runs LoadISISNexus as a sub-algorithm. LoadISISNexus populates the instrument parameter map. re #542.