Implement tools/Linux/Ubuntu scripts to build dependencies. TODO: cmake and tundra build.
Ignore linux Tundra executable.
Implement linux scripts to run cmake and build tundra.
Update windows cmake script. TUNDRA_DEP_PATH is gone and its preferred to pass URHO/MGL_HOME via cmake params not env variables. Makes things a lot cleaner and more compatible with other OS build scripts.
Tundra: Fix linux run() entry point to have correct namespace.
CMake: Remove TUNDRA_DEP_PATH, it is a legacy variable not used for anything sensible. Best be specific and demand env variables or cmd line params for each required dependency. Remove using CACHED_ENV and ENV_ in general in internals, XXX_HOME should be used instead. Cache is written to correctly pick up any previous given values when running cmake without our scripts (eg. inside visual studio on cmake file changes).
Ignore new style postfixed /build-xxx folders.
Merge remote-tracking branch 'origin/master' into linux

Conflicts:
	CMakeLists.txt
Linux scripts: Change urho build dir back to 'Build'. Seems there are some hardcoded things in FindUrho3D.cmake that break includes if its not exactly 'Build'.
Give Travis CI a spin with quick config to run whole build chain on linux.