Improve SQUID for new checks

- split selectionStatement and refine switch statement
- introduce nullptr rule
update common check list files

7 additional checks
check collapsible if candidate
check hardcoded IP
check for line indention
check for missing curly braces
check for special file handling

this might be very specific - but I need it.
check for certain defintions (BOOL, WORD, ...)

shall be replaces by C++ types
check for useless parentheses
add description for NewLineAtEOF and NoTabCharacter
remove comment