Add commented reactive banana example to the repository.

Reason:
- unable to install reactive-banana-wx module due to
        array-0.4.0.1 requirement
Add expression parser with +,-,* and / operations.
Add parentheses parsing.
Add threepenny-gui dependency and remove reactive-banana
dependency.
Split files to library and executable.
Add skeleton code for first example (2 cells: input and output,
function processing).
Add comentaries to the library.
Add text dependency to cabal file.
Add functions for parsing, evaluation for Expressions and convertion
from Integer to String.
Add events and behaviours for first example (one input, one output
fiels with function parsing. Without referencing.)
Add .swp files to gitignore.
Added cell references to parser

They parse in a dummy way.
Example of recursively computed table

Binomial coefficients calculated by magic. The spreadsheet will be
calculated the same way, hopefully.
Merge pull request #3 from andrejbauer/development

Rezultati govorilne ure.
Merge branch 'development' of https://github.com/LukaK/ExcellingCabbage into development
Fix bug in .gitignore regarding .swp files.
Add multiple cells without reactive component.
Add enter event trigger for changing cell functions.
mend
Add monad for output cell.
Make more intuitive file structure.

Add file for parsing.
Add file with reactive structures.
Add file with main program.