More abstract table access

Apparently you CAN insert table names into SQLite statements if you
encapsulate them in double quotes.
New SQL command to simplify parameterization

Now all functions of MTG_Cube call a self.sql function. This function
properly formats all parameters and inserts them into the SQL query, and
executes the command.

Next up: Make sure all functions necessary to statistics exist. Also,
try to generalize functions to take in any number of restrictions
(filter columns).
Infinitely expandable get_distinct and get_number functions, and graphing!

Graphing requires matplotlib, I installed Anaconda to get it.

get_distinct and get_number now accept any number of parameters, and
will restrict the data set further for every column name and column
label added.

Example: To get all the possible converted mana costs in black, you
would call:
cube.get_distinct('CMC', 'Color', 'MONO_BLACK')
To get all the possible CMCs of creatures in black, you would call:
cube.get_distinct('CMC, 'Color', 'MONO_BLACK', 'Card_Type', 'CREATURE')
Working graph

The graph now displays the corresponding color for each mono-colored
segment.