#94 TA_FuncTableAlloc description is wrong

[Alexander Trufanov]

According to https://sourceforge.net/p/ta-lib/code/HEAD/tree/trunk/ta-lib/c/include/ta_abstract.h#l121 TA_FuncTableAlloc must be able to return all function names:

Passing NULL as the group string will return ALL the TA functions.

On practice it returns TA_BAD_PARAM in case group is NULL:
https://sourceforge.net/p/ta-lib/code/HEAD/tree/trunk/ta-lib/c/src/ta_abstract/ta_abstract.c#l273