SVN fixes and support for reading from file

The SVN tree now has support for reading the image from file ('-F' paramter), which is the first stage of implementing a 'control' windows to allow fine tuning/optimization of libdmtx paramters.

There are also multiple fixes related to libv4l capture, which (should) allow capture from pretty much any webcam regardless of supported formats. Specify 'RGB3' pixelformat on the command line and libv4l will auto-magically convert the camera feed to that format.