* Move perform_feature_checks() before GCC configuration to allow compiler
option tests to be recognized during the first build when no cache file
exists.
* auto-save was broken for all sub sheets with are in a sub-directory of the project directory. (reason wxFileName::Normalize(), used to create the absolute path has issues with filenames starting by '$', perhaps due to env var which also start by $). the auto-save prefix is modified ( now AUTOSAVE_PREFIX_FILENAME which defines "_save_" ) and defined only once.
* auto-save files from sub-sheets were not found due to the fact the path was not set (fixed by Blair Bonnet's patch)
The GCC/LLVM specific handling for adding -fvisibility options is later in
this file, so these options would only be added on the second invocation
without clearing the cache.
* Use only double to store zoom levels in class BASE_SCREEN (int type is not working for eeschema or page layout editor) (this fix Bug #1450551, Assertion failed on wxRound() when zooming)
* Fix crash in all apps but Pcbnew when a grid or a zoom was selected from the popup menu.
* Modify default hotkeys for Next Grid and Previous Grid: the initial key was a dead key, not suitable as hotkey. the 'N' and Shift N keys are used instead (with a change for unfill zone hotkey)
* Modify code in EDA_DRAW_FRAME::SetNextGrid() and EDA_DRAW_FRAME::SetPreviousGrid() to make them compatible with other editors than the board editor.
added the example gen_gerber_and_drill_files_board.py in demos, which shows how to do that.
Fix a Printf format issue (shown in Debug mode) in Libedit (%d used for a size_t, changed in %zu)
Important note: from a python script one cannot plot the palge layout, because the page layout template file is not stored in the board file, but it is part of the project.
Because when using a python script, the project is not loaded, the page layout template is not known.
Trying to plot it crashes the script.
Fix a i18n issue in field names when loading a component, if the language was changed during a session, and kicad not restarted (see Bug #1448654).
However changing the language needs restarting kicad, in order to have all messages or menus translated.