Automation - Github actions

[Baklap4]

Within the main repo we've added a bunch of automation for performous It'd be nice to also apply the findings there to here and create faster releases and build checks.

Todo

• [x] Add github workflow (copy paste from performous/performous)
• [x] Add Nightly link to readme
• [x] Add PR commenter (copy paste from performous/performous)
• [ ] Create buildscript for Windows
• [x] Create buildscript for Linux
• [ ] Create buildscript for OSx
• [x] Add CPACK within the main cmakelists (copy paste from performous/performous)
• [ ] Add uninstall target
• [ ] Windows - Make sure to install within Program Files/Performous/composer
  • this way the directory becomes:

    ProgramFiles/Performous/Performous/Performous.exe
    ProgramFiles/Performous/Composer/Composer.exe

• [ ] Add Github Issue forms

[Baklap4]

Couple of items are already done in latest master see PR #46

[Baklap4]

@twiecki please watch this issue for new windows binaries :)