Also updated class_maker.py

Fixes all flake8 3.7.9 warnings as part of the Python 2->3 transition.

After moving get_spectra_selection the mocks were looking for the
function in the wrong place

Re #25548

Double clicking workspace now shows Spectrum/Colorfill option
Adds PlotTypeDialog that shows the Spectrum/Colorfill options, then
shows either the Colorfill plot, or the Spectrum dialog.
Add test_spectraselectiondialog, and test_plottypedialog.

Refactored PlotTypeDialog to not contain SpectraSelectionDialog, now it
just creates it anew. Adapted test to new behaviour

Change assertTrue(a >= b) to assertGreaterEqual(a, b)

Change assertTrue(a < b) to assertLess(a, b)

Change assertTrue(a <= b) to assertLessEqual(a, b)

Change assertFalse(True) to fail

Change assertTrue(a is not b) to assertNotEqual(a,b)

Change assertFalse(a is b) to assertNotEqual(a,b)

Replace variable names such as "plot_as_distribution" to
"normalize_by_bin_width" for clarity.

Tests were failing because get_axes_label was returning an empty
latex string "($$)" if a workspace had been plotted as
distribution.

Move free functions to anonymous namespace

to continue line color cycle after conversion.

Preserve title when overplotting scripted fig

Refs #24768

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

Axes.get_lines() changed its behaviour when error bars are plotted
in version 2. This change covers both versions.