Case sensitive search

Add tool button menu to FindReplaceWidget with an entry to select
case sensitive search.
Whole words only and RegExp search (#63)

Added two more actions to tool button menu in FindReplaceWidget. With
these actions the user can activate searching only for whole words and
searching using regular expressions.
Merge branch 'develop' into feature/search-options-#63
Merge branch 'feature/search-options-#63' into develop