copy particle position data to persistently mapped vertex buffer
Merge pull request #116 from lanice/libelemate_tests_114

Libelemate, google test, upgrade to glow 0.3.0+
update terrain height buffer in changed ranges only
enable back face culling for the terrain
update terrain type buffer only as needed
less dramatical abort if wrong working directory is set
replace glBufferStorage (requires OpenGL 4.4/ ARB_multi_bind)
fix particle vbo update, don't try to map the buffer persistently (pre opengl 4.4)
Update README.md
use smaller texture formats (needs testing on different platforms)

- could improve rendering performance
drop bedrock terrain in the middle of the deleted lava particles #92
don't set the hand's bounding box, which was not axis aligned #92
remove debug code #92
add low res terrain temperature texture per tile, with testing data #111
Merge pull request #118 from lanice/buffer_update_performance

Buffer update performance
Merge pull request #124 from lanice/particleCollision_92

Particle collision 92
Merge remote-tracking branch 'origin/master' into temperature_111
Revert "add low res terrain temperature texture per tile, with testing data #111"

create separate terrain tile instead of temperature as attribute of the existing tiles

This reverts commit 0c1ae737401097b79780a9f4c18b29dcd3b71bb2.
use quadratic terrain tiles only (as needed), makes the code a bit simpler #111
minor height range fix #111