Remove old code
Re-implement MQ² with a plugin system

This re-write re-strustrure the code allowing the design of a plugin system.
This plugin system should allow easier integration of more input format.

This commit provides the first implementation for MapQTL output.
Let's ignore the .map files
Adjust file name
Split the code into two functions so that the plugin can be retrieved separatly
Add a session_name variable to the plugin

This variable is used by the UI to display what type of session are
needed for the analysis
Raise exception if the plugin didn't work and didn't generate the expected file
Check if the session is already in the list before adding it
Add option to strip down the quotes when reading in a csv file
Add the CSV plugin allowing to parse R/qtl output
Convert the row to string before writing them
Raise an exception if the dataset can not be handled by any plugin
When raising exception for no session found, list the possible sessions
Add the plugin to support Excel input
Update the README
Add links to MapQTL and R/qtl in the README
Update end-user documentation

Add a new page on how to prepare the data for MapQTL, R/qtl and
in CSV/Excel if using another tool.

Add another new page on how to create your own plugin
Fix the integration of the Screenshot in the data file

Using `.. image::` the image was not correctly represented in the pdf
documentation, using `.. figure::` fixed it.
Import the release/version from MQ2 itself.

The release number is required to have the version in the pdf.
Add a pdf version of the documentation with the sources