Delete unused files.
(ie all the org.cts.op.projection.grids package + FrenchGeocentricNTF2RGF)
Implement a new method of creation of NTv2GridShiftTransformation,
so that the class from package org.cts.grid are used only by the class NTv2GridShiftTransformation,
which make the code more understandable.
Merge pull request #37 from jparty/refactorCode

Refactor code