Fancy display options and better appearance; settings categorization

All changes are made on top of your **current** master d463dc85c86672d210c62139574626d6526640c5. You should be able to merge without any conflict.

**Nett Changes:**
\+ No space before unit
\+ Hide B in unit
\+ Always show suffix (when zero speed is hidden)
\+ Add new categories Unit Settings and Indicator Appearance
\* Show speed in exact position in two-line mode
\* Reorganize settings into proper categories
\* Move category names to strings.xml
\* Some minor optimizations
Just renamed and re-purposed the method to refresh the "setEnabled" value for all settings. Also, no need of if-else block. Just use the condition as boolean :)