Merge pull request #117 from abelsiqueira/refactoring

Improve initialization of dictionaries
Improve TikZ backend

Use a more efficient string concatenation method based on
http://www.skymind.com/~ocrow/python_string/.

Close #47.
Implement the column setting option for yaml
Add column information on file-format.rst and change to col_* instead of col-*
Merge pull request #119 from r-gaia-cs/tikz-str-as-list

Implemented improvement at TikZ backend
Add comment about column index and default information
Merge pull request #120 from abelsiqueira/columns

Implement column handling
Add objective function verification
Add parser infeasibility option
Test for number of columns
Update bash-completion for optimal values
Add compare flag to either use exitflag or optimalvalues
Change extra flags to only --unconstrained