Add RTF output to RTF Translator

[humdinger]

This is hrev44428.

While the RTF translator can convert to plain text and StyledEdit format, it currently cannot convert the other way around, i.e. text to RTF. From "translate --list":

name: RTF text files
info: Rich Text Format Translator
version: 0.6.0
  input:        'RTF ' (TEXT) 0.7 0.9 text/rtf ; RichTextFormat file
  output:       'TEXT' (TEXT) 0.3 0.6 text/plain ; Plain text file
  output:       'STXT' (TEXT) 0.5 0.5 text/x-vnd.Be-stxt ; Be styled text file

[siarzhuk]

Result of corresponding GCI 2013 task.

[pulkomandy]

The patch doesn't convert styled text attributes to RTF. So it gives acceptable results only for text/plain sources. Isn't there an RTF parser/generator library we can use? If not, we'd have to write one...

[pulkomandy]

I added a GCI taskfor the 2014 run to complete this.

[pulkomandy]

Done in hrev48534.