RegexCheatSheet.pm: adding support for simple character classes like "regex [1-6]" etc
RegexCheatSheet.pm: Removing are_same_case - already handled by are_valid_char_classes
RegexCheatSheet.pm: Locking down regex for simple character matches & added tests
Merge pull request #243 from mintsoft/RegexCheatSheet

RegexCheatSheet.pm: adding support for simple character classes