Better imports for bogus CSV files

So I got to convert some CSV files with newlines in the middle of a row, or bad email formats, that triggered various vCard generation errors.

This version has improved handling of badly formatted CSV files
Also provides new option --max-vcards-per-vcard-file option to deal with Grommunio's webapp that doesn't seem to want more than 490 vcards at once.

GUI / prebuilt executables

The main feature of this release is the addition of a GUI for csv2vcard, which should easen the usage.
GUI also has import/export settings feature for quick configuration.

This release also adds pre-built Windows executables.

Please note that some AV software will complain about the executables, because they contain Python (whoo!!! how bad).
Feel safe to use them, they are signed with my company's OSS key.

Highly improved vCard generation, now with CLI app

This release rewrites the vCard generation code, adds a CLI interface as well as various enhancements.