String Management

`GB.AddString`	Adds a string to another one.
`GB.ExtendString`	Expands a string.
`GB.FreeString`	Releases a string.
`GB.MatchString`	Checks if a string matches a specified pattern.
`GB.NewString`	Creates a new string.
`GB.StringLength`	Returns the length of a string.
`GB.SubstAdd`	Substitution callback helper.
`GB_SUBST_CALLBACK`	Substitution callback datatype.
`GB.SubstString`	Substitutes strings inside a pattern.
`GB.ToZeroString`	Converts a Gambas string into a temporary null-terminated string.

C Library String Functions Replacement

`GB.strcasecmp`	Compares two ASCII strings, by ignoring the case.
`GB.strncasecmp`	Compares two ASCII strings, by ignoring the case, up to a specified length.
`GB.tolower`	Converts an ASCII string to lower case.
`GB.toupper`	Converts an ASCII string to upper case.