Fix #46 -- TA-Lib functions which require inputs besides close do not work properly

[lukeplausin]

Hi, I believe this fixes the broken TA-Lib functions.

The process is -

• Check the _tabstract object to see which inputs are required
• If more than one input is required, build the inputs using the named variables
• If not, use the old code

Tested with these functions:

• SMA
• RSI
• MACD
• ULTOSC (non trivial)
• MFI (non trivial)