Update regex module

### Summary
Here we go, a general update:
* Updated PCRE to v8.35 with UTF support.
   * :point_right: This has been compiled with ```--enable-jit --enable-utf8 --enable-unicode-properties```
* Added new natives: 
   * ```regex_compile_ex```: mainly to allow to use directly ```PCRE_*``` flags (like SM).
   * ```regex_match_all_c``` and ```regex_match_all``` : by Nextra, to retrieve all matches (with ```regex_subtr```)
   * ```regex_replace```: Search and replace function.
* Added a new stock: ```regex_match_simple``` (Same as SM)
* Updated ```regex_subtr``` to increase static buffer size same as AMXX and to make it UTF-8 safe.
* Update few things internally (Some cleanup, AMTL, increased max. number of sub-pattern, etc.)
* Included a test plugin (mainly to check ```regex_replace```)
* Updated documentation.

### Technical notes about ```regex_replace``` implementation
* Scott, you may want to pay attention to this native as there is quite a lot of code, even though it's not that complicated. I've put many comments.
The native uses ```MatchAll``` to retrieve all sub-patterns which has been introduced by Nextra, but because it was not working properly you will notice I had to refactor it. 
* You may also want to know that some logic has been stolen from [PHP source code](https://github.com/php/php-src/blob/master/ext/pcre/php_pcre.c#L1032) for:
   * ```MatchAll```
   * ```MakeSubpatternsTable```
   * Some logic to get backreferences
* Native supports some format specifiers/flags for ```replace``` parameter. This has been taken from C++/C# implementation.
* Tests used in plugin has been stolen here and there, and I have added some to test edges/utf cases.
* Considering it passes 200+ tests, I guess implementation is not that bad.
* Good luck :trollface:.

General flags to control how the string is replaced. See REGEX_FORMAT_* defines.