Non-standard symbol names for BNF grammar

[kaby76]

While using the grammars-v4/bnf grammar for creating an ebnf, I noticed several errors:

• LPAREN, RPARENT and the other symmetrical character symbols are reversed on how it is usually defined.
• oneormore is actually called a "grouping" in standard EBNF terminology.
• optional_ is okay because that is the standard EBNF terminology, but it might be better called "zero_or_one".