Add an option to not add newlines after each line in the properties file

[pasi-paasiala]

New lines after every line are a bit problematic for us, since we are manipulating the properties files also by external tools used by external translators. In this process the new lines get lost and when rbe puts them back, we get a lot of noise in the diffs.

[achimmihca]

I have the same issue. The newlines are also problematic when doing block editing (i.e. editing certain columns of multiple adjacent lines).

Furthermore, I think the order of the original keys should be preserved when saving (see #77 )