Replaced various Replace()-calls with Sanitize()

- replaced Replace("-","_").Replace(".","_") with a more convenient TStringHelper.Sanitize() which takes care of all nonalphanumerical chars. Without additional params everything "non-valid" is replaced with the underscore "_" character (so an existing "_" is replaced with "_" - which gets rid of the need to write more parameters than needed)
- added some small tweaks avoiding multiple Sanitize-calls (Sanitize only once instead in if-then-else + end)