Clarified need for `-s` to get character encoding info.

Closes #1724, #1725.
Strip querystring in ODT write

* Resolve #1682
* Strip querystring from filename before rendering ODT files, ODT cannot
handle querystrings in files.
Merge pull request #1727 from toddsifleet/tws-fix-issue-1682

Strip querystring in ODT write
TWiki Reader: add new new twiki reader
TWiki Reader: add basic syntax test
TWiki Reader: update documentation
ODT writer:  Correctly handle images without extensions.

Closes #1729.
Merge pull request #1726 from AlexanderS/twiki-parser

TWiki Reader: add new new twiki reader
Fixed README and pandoc.cabal for TWiki reader.