Adding gsub function
Adding gsub function
Adding capture group test case
Merging remote
Merge upstream into adding_gsub_function
Adding replace function

* renamed gsub function to replace
* reordered replace's function arguments to be much more readable
* added support for replacement (Regexp) options
Replacing replace's options to flags
Merge pull request #1855 from jakebellacera/adding_replace_function

Adding replace function