Merge pull request #9 from kangaroomadman/master

Corrected '--default-track' boolean value when user requests AC3 track to be default using '--default' argument.
Fix: DTS track selection / Added: Batch convert option

Fixed: The script did convert the last DTS track found and not the first one (as it should and as stipulated in the Readme).
Added: When "force" option is set to true, not just the first one but *all* available DTS tracks are converted to AC3
Fixed typo
Merge pull request #10 from janeczku/master

Fix: DTS track selection / Added: Batch convert option
bug #12 - make DTS look for A_DTS or DTS

newer mkvtoolnix reports DTS tracks as "DTS" instead of "A_DTS" as it did previously.
fix issue #12

changed strings for AC3 and DTS to match the output of the new mkvtoolnix
fix issue #11

This seems to be the best way I can see to force english so the string compares work.
escape ( in regular expression