Fix possibility of degenerate OcclusionBuffer triangle edges causing a floating point division by zero. Thanks to nemerle for noticing this.
Add initial support for 64-bit Android ABIs.
For Travis CI - double the time to wait for AVD to start.
AVD with API level 21 seems to take longer to start. Also when the AVD failed to start in time, CI now skips the APK installation/launching test and considers the whole build as passed.
For Travis CI - switch CI build to use Android build environment.