tsql grammar contains symbol conflicts for PHP target

[kaby76]

After working on cleaning up the PHP target runtime, I am going through and testing the target on selected grammars in this repo. Unfortunately, the Antlr tool generates name conflicts whenever there are names that are identical when not considering case. Therefore, a lexer rule symbol "FooBar" will conflict with parser rule symbol "foobar" because "FooBar".ToLower() == "foobar".ToLower().

Therefore, The tsql grammar won't work with PHP because of symbols CLUSTERED/clustered, OPTION/option, ALGORITHM/algorithm, TIME/time.

The grammar also has conflicts for EMPTY and TOSTRING, both are which are symbol conflicts with the runtime.

[KvanTTT]

Linked issue in the ANTLR repository: antlr/antlr4#3462