- in Preferences window removed the Import/Export Preferences buttons because they are redundant with the entries in the File -> Menu -> Backup. and added a button to Restore Defaults
- when in Basic mode the Tool type of the tool in the Geometry UI Tool Table after isolating a Gerber object is automatically selected as 'C1'
- let the multiprocessing Pool have as many processes as needed
- added a new Preferences setting allowing a custom mouse line width (to make it thicker or thinner)
- solved issue #292 where a new geometry renamed with many underscores failed to store the name in a saved project
- the name for the saved projects are updated to the current time and not to the time of the app startup
- some PEP8 changes related to comments starting with only one '#' symbol