Improve rust-style identifiers code

There is no reason to heap allocate for each individual character (or each group of characters?) when the allocated collection isn't even going to be used anyway

Author: LoganDark

doc/nom_recipes.md

@@ -115,7 +115,7 @@ letters and numbers may be parsed like this:
 use nom::{
   IResult,
   branch::alt,
-  multi::many0,
+  multi::many0_count,
   combinator::recognize,
   sequence::pair,
   character::complete::{alpha1, alphanumeric1},
@@ -126,7 +126,7 @@ pub fn identifier(input: &str) -> IResult<&str, &str> {
   recognize(
     pair(
       alt((alpha1, tag("_"))),
-      many0(alt((alphanumeric1, tag("_"))))
+      many0_count(alt((alphanumeric1, tag("_"))))
     )
   )(input)
 }