regex: add/document missing offset param (#1175)

* Regex Little Changes

* Prevented to triple and double call `strlen`.
* More informative message on `if (offset >= len)`.
* Add missing parametr in navite `MatchRegex`.

* Regex Little Changes v2

* Using `strdup` instead `strcpy`.
* Replaced NULL to nullptr.
* Removed note about MatchOffset.

Co-Authored-By: Headline <[email protected]>

* Removed padding.

Co-Authored-By: Headline <[email protected]>

* Removed more padding.

Co-Authored-By: Headline <[email protected]>

Co-authored-by: Headline <[email protected]>

plugins/include/regex.inc

@@ -199,12 +199,13 @@ native Regex CompileRegex(const char[] pattern, int flags = 0, char[] error="",
  * @param regex         Regex Handle from CompileRegex()
  * @param str           The string to check.
  * @param ret           Error code, if applicable.
+ * @param offset        Offset in the string to start searching from.
  * @return              Number of captures found or -1 on failure.
  *
  * @note Use the regex handle passed to this function to extract
  *       matches with GetRegexSubString().
  */
-native int MatchRegex(Handle regex, const char[] str, RegexError &ret = REGEX_ERROR_NONE);
+native int MatchRegex(Handle regex, const char[] str, RegexError &ret = REGEX_ERROR_NONE, int offset = 0);
 
 /**
  * Returns a matched substring from a regex handle.