* field that are overwritten from every class instance SHOULD NOT be "static"
* some field could and was converted to local variables
* add missing "private" qualifier here and there
* action bar may be null, added checking for this
* remove wrapping all method body in try-catch, moved it to method call
* removed redundant field and local variable initializations
* single-char string replaced with char
* redundant qualifiers ("SettingsActivity.this" etc.) was removed
* remove all trailing spaces
* some files used spaces instead of tabs like the rest of codebase - fixed
* make use of IDE "optimize import" feature
* make use of IDE "auto format" feature to fix some missing spaces here and there
