Added encoding to preferences

[dkrey]

I've encountered a Bug on MacOS catalina: If no encoding is set, the build fails with an error like this:

/bin/sh: -c: line 0: unexpected EOF while looking for matching `''
/bin/sh: -c: line 1: syntax error: unexpected end of file
[Finished in 0.0s with exit code 2]
[cmd: echo 'ascii' codec can't decode byte 0xc3 in position 2747: ordinal not in range(128)]

So I did added an encoding option to the preferences and added it to the appropriate function. The editor also took the liberty to remove some trailing whitespaces :)