Fix enum usages

[jb-lopez]

The enums located in namespace LupeCode\phpTraderNative\TALib\Enum are not coded like modern enums. Whether this is due to me misunderstanding PHP enums, or PHP enums evolving since they were introduced, I can't say.

The code technically works, but has issues. There have been a few gotchas discovered, like #18, #17, and #16.

Updating the code to the modern PHP enum formatting is a must.