Added pre-commit hook

Also: astyle generates backup files. Ignore them
Removed else block
Refactored requirement checks
Removed unneeded variable
Fixed conditional

There can be other return values than 1 which also evaluates to false.
Added missing exit 1
Removed unneeded comparison
Fixed newline error of astyle
Added comment to unclear line
change directory to root dir of project, go back to working dir afterwards
run 'astyle' on include/libreset/set.h
run 'astyle' on src/libreset/util/attributes.h