Abnf To Antlr Files

Add case-insensitivity for char-val nodes per https://tools.ietf.org/html/rfc5234#section-2.3 which states...

ABNF strings are case insensitive and the character set for these strings is US-ASCII.

Hence:

 rulename = "abc"

and:

 rulename = "aBc"

will match "abc", "Abc", "aBc", "abC", "ABc", "aBC", "AbC", and "ABC".

To specify a rule that is case sensitive, specify the characters individually.

For example:

 rulename    =  %d97 %d98 %d99

or

 rulename    =  %d97.98.99

will match only the string that comprises only the lowercase characters, abc.