New Feature:
	- JGenfit reads the value of maxpdb on the advanced common parameters, all the models with PDBs takes the same number of PDBs as set in maxpdb. In the user interface when this maxPDB parameter is modified automatically the file is changed in memory. Also it is checked when a file is opened. So, the number of PDB could increase or decrease
	- Editing the model, now when click in the value column when it detects that the value starts by "PDB File " a browser to select the file is opened then user can select easily the file.

Bug Fixed:
	- I found that it was not possible to edit the last model of each file.

Some changes:
	- some classes has been refactorized and I have created File utils and File Dialog in order to keep together all the common classes