Milestones and targets for future OpenPiv versions.

v 0.1
+ all functions should be unit tested
+ all functions should be correctly documented
+ the basic api structure should be clear and defined

v 0.2
+ Lavision file format reader
+ Hdf5 output
+ at least one advanced processing algorithm, ( 1st order, 2nd order )

v 0.3
+ data display submodule using matplotlib
+ post-processing facilities

v 0.4
+ basic gui for image processing. The gui will allow to select image directory
processing parameters, algorithm, etc, but not display result at the moment.

v 0.5
+ Gui post-processing and data visualization
