Add an option CmdLine.cpp and IApp.cpp to leave unparsed values in an array.

[ggarra13]

The idea is to support loading an arbitrary number of images with the values that were not parsed. So you can then do:

$ mrv2 *.exr

Loads all exrs in current directory instead of three clips and a comparison one as mrv2 has now. It can load directories, but sometimes you want to filter the files by extension.

[ggarra13]

I implemented this as PR #116 .