refocus active cell on dialog close

if there is one

Otherwise, the cursor is lost on kernel restart, etc.
Added tests directory
Added test files, and basic tests
Now uses relative path to find files
Added exporter tests
Added some filter tests
ignore_case->case_sensitive (boolean opposite)
add 'all' extras

which should get everything
add pandoc to install docs
RST capitalization fix
s/ConfigurableTransformer/Transformer
s/Test_/Test
Fix, ansi2latex style-less code support
Allow ansi2latex function to recognize ansi codes without styles
Fix ansi2latex color remainer of string.
Exclude nbconvert testing config files from iptest interpretation.
Add nbconvert dependencies to TravisCI config
Travis, test without exclusion...
Removed double space
Add __init__.py files for files directories
Re-enable files directory exclusion.