CURA-12101
The printer parses the machine_start_gcode to allow selecting the filaments mapping at start time, without it the user has to set the filaments in fixed order. This is probably a security to ensure the proper filament is loaded at start.
Converted doxygen style comments to reStructuredText style in the files found in Cura/cura/API directory recursively using the script dox_2_rst.py (provided in the Uranium repo). Comments were manually checked and changed if needed.
Comments from the hidden attributes in the class CuraAPI (_acount, _backups, _interface) were moved to the public property getters, so they docstrings are exposed to the user.
