Change image link (now relative)

https://github.com/blog/1395-relative-links-in-markup-files
A horizontalOffsetPlane for things like train tracks and whatever.
Merge remote-tracking branch 'movingblocks/develop' into smallBugfixes
Adds some more properties and tweaks all things related to HDR rendering (in combination with the recent post-processing effect additions).
Merge pull request #443 from skaldarnar/develop

Increased initial distance for dropped blocks and made inventories persi...
Adds some more properties to the "sobel" edge detector shader and cleans up some other post-processing related things.
Fix for StringMap serialization.
Merge branch 'develop' of https://github.com/MovingBlocks/Terasology.git into develop
Tweaks various rendering related things and adds a new custom (less repetitive) ocean/water simulation/animation algorithm.

- Adds that the normals for the offset water vertices get calculated using multisampling and differentiating
- Separates grass animation from water animation (water animation is only available via the "Insane" and "Epic" graphics quality settings from now on)
- Adds various properties to control the water simulation
- Adds support for different quality settings for the water simulation (octaves used for the wave generation can he varied)
Terasology. New block family. Fences, rails and lader as bonus
Adds various new rendering related features and tweaks.

- Adds real refractive surfaces (third render pass for solid chunks - yey).
- Renames various shader parameters and adds many new properties
- Removes faked refractive water surface and adds a new config option to enable water refraction
- Tweaks shading of ocean waves on "Insane"
- Some more things I forgot...
Added support for a dependencies list in mod.txt. This informs the build, the projects created for mods, and the selection of modules ingame.
Also improved generation of mods by the build script. If you add a new mod to settings.gradle and gradlew, then the mod directory and a skeletal mod.txt will be generated. Additionally the task 'mods:mymodname:createSkeleton' will generate a full directory skeleton with folders for all asset types and source code.
Merge branch 'develop' of https://github.com/MovingBlocks/Terasology.git into develop
Fixes that activating the "Insane" graphics quality setting without "ANIMATED_GRASS" lead to shader compile errors.
Packs some of the many chunk shader parameters into Vector4s and tweaks ambient lighting and refraction water intensity.
Tweaks refraction intensity and adds that various opaque renderables (like items and small blocks) get rendered to the refraction FBO.
Merge #438 from @AWFeldick first even though it also exists in #446 :D
Merge #446 from @small-jeeper for auto-adjusting fences, rails, and a ladder!
Merge #444 from @mkalb to make an image link relative
Tiny bit of cleanup/commenting