Correct send mail function with Linux

1) Add the "from address" needed by SendMail in the settings
2) Correct a problem of strings translation in send mail function
Merge remote-tracking branch 'upstream1/master'
Improve stings for translation
Improve strings for translation

- Change and improve some strings
- remove all untraslatable strings from pot file
Merge pull request #78 from Ptizef/master

Correct send mail function with Linux
Modify CMake environment to allow build without OpenGL.
Further correct language string access in GRIB PlugIn.
Remove broken wxLANGUAGE_ARABIC_UAE languge selection. (FS#512)
Merge branch 'master' of https://github.com/OpenCPN/OpenCPN