completely overhauled the project code

* moved specific backup logic into BackupTask which can be run in a separate thread
* revamped backup scheduling, now there is only one config option which can hold both an interval or backup times
* BackupTickHandler simplified, only contains scheduling and backup checks now
* command structure completely overhauled, seperate "sub-commands" are now split into independent classes for clear seperation of logic
* ConfigHandler now provides methods for simplified retrieving and setting of config values
* changed parsing of schedule times, moved all logic into seperate Time class for easy parsing and comparison
Merge branch 'overhaul' into dev
* bumped version to v1.7.10-0.5.1
Merge branch 'dev'
Update README.md
+ added option to set compression level for zip archives (thanks to /u/PAPRPL8)
Merge branch 'dev'
Merge branch 'master' of https://github.com/szernex/YetAnotherBackupMod
Merge branch 'master' into dev