Show only appropriate parameters  with data types  in setting dialog and add a specifique set of colours for wind
Change label
Correct settings display anomalies
Add slider to set overlay transparency
Some Display Improvements

1) set the overlay maximum size equal to the screen size
2) add one decimal for small  number values rendering
3) improve some overlay colors selection
Slight code improvement
Merge remote-tracking branch 'upstream1/master'
Correct some display problems with Linux (Ubuntu 13.04)

1) Constants use not accepted by compiler
2) Use "SetTitle" instead of "SetLabel" to display file name in the grib
dialog
3) Suppress  bad and useless parameters to display values and units in
the dialog
4) The slider need a "fixed" width to be  correctly displayed
Merge pull request #77 from Ptizef/master

Show only appropriate parameters with data types in setting dialog and add specifique set of colours for wind rendering