Function: contains

--Usage--
> contains(some_string, match: to_search_for)

Does one string contain another at any position?

--Parameters--
| @input@	[[type:string]]		String to look in
| @match@	[[type:string]]		String to look for

--Examples--
> contains("abcdefg", match:"abc")    == true
> contains("abcdefg", match:"defg")   == true
> contains("abcdefg", match:"abd")    == false

--See also--
| [[fun:match|match / match_rule]]	Does a string match a regular expression?
| [[fun:chosen]]			Is the given choice selected in a multiple choice value?
