Cinnamon: problematic install and theme incomplete

Thank you for this program, very neat. I think such a tool has the potential to become a default in some distribution - like Redshift for example.

I use **Linux Mint Cinnamon 19.1**.

I installed the .deb based on python 3.6, with dependencies.

### Install problems
After install no icon was present. It launched with "automathemely --manage", I could modify settings, but it wouldn't work. "automathemely --restart" shows a popup "INFO: restarted the scheduler", but themes wouldn't start.
After relogin, the icon was there, but theme still wouldn't change.

I deleted the configuration files, launched in console "automathemely" and then it worked.

### Theme partially supported
- the drop down menu for "desktop" in the GUI is [greyed out](https://ncloud.zaclys.com/index.php/apps/files_sharing/ajax/publicpreview.php?x=1920&y=593&a=true&file=automathemelynodesktop.png&t=AfWqTfnpAG6xx6x&scalingup=0). I can enter the desktop theme's name in user_settings.json, and then it works
- cinnamon theme app is divided into [five categories](https://ncloud.zaclys.com/index.php/apps/files_sharing/ajax/publicpreview.php?x=1920&y=593&a=true&file=automathemelycinnamonthemeprefs.png&t=kYs9wD292pWTKDD&scalingup=0). I have not found a "look and feel" global option to change the theme like in KDE. This results in Automathemely not changing window decorations for example.

Start by reproducing the installation and startup flow on Linux Mint Cinnamon 19.1, using the reported `automathemely --manage`, `automathemely --restart`, and `automathemely` commands. Inspect the generated configuration, including `user_settings.json`, and the Cinnamon theme handling. Done means installation and relogin leave the scheduler working and the supported Cinnamon theme settings behave consistently, including desktop theme selection.

Written by the indexing model from the issue text.