Update strings.xml

Fixed some typos on the original translation by me.
Included latest app strings.
Tried to avoid renaming core Kernel feature names, like Hotplug, IO Scheduler... So people doesn't get confused when asking/sharing values.  
* Some strings may be too long, will try to adjust if really needed.
* Recommend changing names in English for: 
- clicky_title (Open GAMMA tweak interface)
- summary_volt_plus_25 (Increase all voltages by (+25mV). Just to be fail reading fool proof.
- summary_volt_minus_25 (Decrease all voltages by (-25mV). Just to be fail reading fool proof.