Add missing semicolon in ParameterDeclaration BNF

When a parameter is declared normally, within the body of the class or
function, then the declaration must be terminated by a semicolon.

(The ParameterDeclaration rule is only used in the Declaration rule.)
Merge pull request #1036 from lucaswerkmeister/fixMissingSemicolon

Add missing semicolon in ParameterDeclaration BNF