Setup for singlefile

[Webatron11]

Change functionality of the writefile function in encoder.py to append to end of file in place of overwriting existing file. This should allow multiple articles to be stored in a single file.

An edit would also need to be made to the decoder to recognize and seperate the articles in a single file

[Webatron11]

Encoder was simple to setup in order to write to a single file. An adjustment to the writefile function will be necessary to work this a bit better.

[Webatron11]

writefile function does not need to be fixed, simply used addtitle function instead. Decoder is being worked on by @Pugalotl