First version of "Clean on exit" - needs to be reworked

Check FIXME comment in MainActivity.java, browsing traces don't get
deleted instantly; Deleting browsing traces through the settings menu
seems to work fine though
Different approach for "Clear on Exit"

Doesn't rely on SettingsV2.java cleaning anymore. Functions well, but
actual clearing behaviour maybe should be thought through again. (When
should clearing happen? Should the complete session be reset?)
Changed string to match behaviour of "Clear on Exit"
Additional browser settings

user can now chose to disable cookies and to disable image loading
(I added a way to disable JavaScript too but it broke the search bar, so
I commented it out for now)
Merge branch 'master' of https://github.com/Minty123/Lucid-Browser
merged
Conflicts:
	res/values-de/strings.xml
	src/com/powerpoint45/lucidbrowser/CustomWebView.java
	src/com/powerpoint45/lucidbrowser/Properties.java