Demomgr

- Fixed bug where startup would fail due to withdrawn dialogues
- Readonly restriction removed from path entries to make corrections less annoying
- Fixed some hectic main window resizing due to long path names
- Removed herobrine

Redesign of some UI components
Addition of "Constant tick offset" button
Some more linux-fixes for pure self-use that really no one cares about i think

- Fixed an oversight setting the date format, and that's about it.

[Why does this stuff always happen]

Alright, here we are. I guess this box is a good place for a changelog, so let me come up with some stuff:
- Play dialog overhaul, now allows to start the game at specific ticks/jump to specific ticks using RCON.
- Deleter has been removed and merged under a new Bulk Operator dialog which is able to delete, copy or move sets of demos.
- Added a "Reveal in explorer" button that as of now has lacking support for anything that isn't Windows explorer.
- Removed ability to select between events.txt and json in the bookmark setter, since allowing to create a desync in data doesn't make much sense.
- Internal DemoDataManager that seriously simplifies working with demo information.
- Internal overhaul of the way demo info is stored.
- Internal config handling/validation overhaul.
- Crash fix when encountering files with broken encoding, these errors are now ignored and the files treated as empty.

First standalone executable distribution of Demomgr using Nuitka.
I would like some feedback on this since I can't really tell if it will even work on PCs without python.