Fix bug #422: Crash: map_cairo_image(): Assertion failed 

There weren't any checking of the status of the cairo_surface_t when reading the image from file. This commit adds it and fixes the bug.
Bug report #420 - The Add keyframe button shouldn't be active if there is not timeline
Bump ETL to 0.4.16, synfig and synfigstudio to 0.64.0 and add splash screen for 0.64.0
Update version in releases and app
Update NEWS
Replace 0_63_06 by 0_64_0 in one missing place.
Add missing files to POTFILES.in
Mac OSX package autobuild script
Fixes for OSX script
OSX build: Fix git repository detection when invoked from source tree
OSX build: Enable macports install without sudo
OSX build: Don't write into system /Applications/MacPorts
OSX build: Write configuration only after we sure have macports built
OSX build: Automatically detect multiprocessor configurations and set make's jobs option
OSX build: Add libtoolize alias
OSX build: Temporary disable multiple jobs for synfig build
OSX build: Disable MACOSX_DEPLOYMENT_TARGET=10.5
Cleanup unused class which raises an error when building on OSX
OSX build: Enable MACOSX_DEPLOYMENT_TARGET=10.5 for everything except Lion
OSX build: Force option to activate python package