Added ability to specify disk buffer size in TCOutput plugin. Fixes #1110

@rafrombrc Hi, I'm creating this PR to easier work/progress on this issue. Could you do initial review? I'll create proper tests and documentation in next commit log, but i would really appreciate your initial thoughts or suggestions.
Thanks in advance. 
Whoops, sorry, I missed that the pack would be recycled when the loop exits, so you can ignore the last bullet point. :)