Added descriptions mapping for LuaScript packages' hooks.

In "ToDoxHook.lua":
- Added "getCurrentDirectory" function;
- Added process to fetch and map C++ headers' descriptions to Lua elements;
- [TODO] Write descriptions from Lua elements for Doxygen output.

In "ToZerobraneStudioHook.lua":
- Writes descriptions from Lua elements for ZerobraneStudio API file.
To avoid cluttering the editor view when selecting a skeleton hierarchy, do not debug draw the child nodes.
Merge remote-tracking branch 'remotes/silverkorn/master'
For Travis CI - switch CI build to use OS X build environment.