2.2

Added string partitioning methods:

• Returning one side
  • suffix_after_first(str_or_char)
  • prefix_before_first(str_or_char)
  • suffix_after_last(str_or_char)
  • prefix_before_last(str_or_char)
• Returning both sides (as std::pair)
  • partition_at_first(str_or_char)
  • partition_at_last(str_or_char)