elang/compiler: Introudce 'break'-statement parser.
elang/compiler: Introduce 'continue'-statement parser.
elang/compiler: Introduce 'var' statement parser.
elang/compiler: Introduce 'const' statement parser.
elang/compiler: Introduce 'throw' statement parser.
elang/compiler: Introduce 'try'-statement parser.
elang/compiler: Introduce |using|-statement parser.