Add coveralls to travis.yml
Fix typo in travis.yml
Add coverage badge
Fix type inference on padarray
Change color slices to colorspace "Unknown"
Allow permutedims to work with tuple inputs
Overlay: default clim using limits, delete limits & colorspace properties

Also try harder to return an image from OverlayImage
io: for multi-image files, switch to interpreting as a timedim rather than spacedim

The motivation is that multi-image files are more commonly temporal sequences
(Think of all the GIFs posted online...)
If this breaks your code (sorry!): manually adjust the properties after calling imread.
Fix unit parsing in NRRD
Partial fixes for converting to Base.Cartesian
Fix buggy label_connected (fixes #115)

This also completes the conversion over to Base.Cartesian
Bump required version of Cartesian pkg
gitignore files created by precompilation
Delete unused `@label` command
Fix # 125

Problem was a nonexistent "ImageDescription" entry in the TIFF
dictionary.  Also cleaned up handling of C_NULL pointers in places.
Make multi image files a timeseries on OS X

Consistent with 2a55a76
Fix the timedim correctly this time
Fix #127 (typo).
Refactor imedge into imgradientxy, imgradient