Declared some boost::regex variables as 'const static' so they will be
initialized at startup. This should give some performance boost as shown
by the new DateAndTime performance test.

Re #0

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 

re #22849
Added new export file for SpectrumDefinition.
Added extra tests for SpectrumDefinition usage.

# 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.

They affect all targets and make it more difficult to control the order
of the includes at a later stage.
Refs #0

# 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.

This reverts commit 480f7776.

Issues on clang:
07:12:15 Undefined symbols for architecture x86_64:
07:12:15   "Mantid::Types::Core::DateAndTime::MAX_NANOSECONDS",
referenced from:
07:12:15       Mantid::Types::Core::DateAndTime::maximum() in
DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::minimum() in
DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::operator-(long long)
const in DateAndTime.cpp.o
07:12:15
Mantid::Types::Core::DateAndTime::operator+(boost::posix_time::time_duration
const&) const in DateAndTime.cpp.o
07:12:15
Mantid::Types::Core::DateAndTime::operator-(boost::posix_time::time_duration
const&) const in DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::operator-(double) const
in DateAndTime.cpp.o
07:12:15   "Mantid::Types::Core::DateAndTime::MIN_NANOSECONDS",
referenced from:
07:12:15       Mantid::Types::Core::DateAndTime::maximum() in
DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::minimum() in
DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::operator-(long long)
const in DateAndTime.cpp.o
07:12:15
Mantid::Types::Core::DateAndTime::operator+(boost::posix_time::time_duration
const&) const in DateAndTime.cpp.o
07:12:15
Mantid::Types::Core::DateAndTime::operator-(boost::posix_time::time_duration
const&) const in DateAndTime.cpp.o
07:12:15       Mantid::Types::Core::DateAndTime::operator-(double) const
in DateAndTime.cpp.o
07:12:15 ld: symbol(s) not found for architecture x86_64
07:12:15 clang: error: linker command failed with exit code 1 (use -v to
see invocation)

Merge to ensure CrystalFieldFunction is available and up to date.

* Make Core::DateAndTimeHelpers::stringIsISO8601() to check for basic
ISO8601 strings as well.
* Add  stringIsPosix() method to DateAndTimeHelpers to check validity of
posix strings.
* Extend corresponding unit tests.
* Add the posix string check to DateAndTime::setFromISO8601().

Re #20969

Re #20969

Re #20969

Makes the function accessible to Types::Core::DateAndTime. The function
was originally using Poco which is not linked to Types. We now use
boost::regex instead.

Re #20969