Adress #FS 1143 & #FS 1311 and other improvements

1- Suppress useless 'range' parameter for wind arrows and replace it by the possibility to set its 'always visible' even if the wind check-box is unchecked and the choice between standard color and values controlled colors as an alternative to the colored overlay.(#FS 1143)
2- add the possibility to set pressure isobars 'always visible' even if the pressure check-box is unchecked.
These possibilities allow to have the main weather informations (wind arrows and isobars) always displayed whatever overlay is selected.
3- Allow selected quickly the desired overlay and display only one at a time( the check-boxes in the main 
window react nearly as radio-boxes)
This points concern discussions and some criticisms in the forum.
4- active the 'size' parameter for waves and current arrows (only default and small size) and add the possibility to choose between single and double arrows.(#FS1311)
5- Save only useful parameters to limit the .init file size.