Since the directory monitoring is now basically working we remove the
project scan thread periodically scanning the project directory.
Each project's directory is scanned only once at the beginning when
calling the function `core.add_project_directory` and is updated
incrementally when directory change events are treated.
The config variable `project_scan_rate` is removed as well as the
function `core.reschedule_project_scan`.
- Added version and license metadata
- Configuration data to be used in configured files to set metadata
- Portable binary and directories in the main install directory
- Binary file installed in correct places for all supported platforms
- Freedesktop AppStream support
- Added missing files install rules