Fix AngelScript compilation due to a wrong letter case.
Source the helpers script after changing to project root directory.

So that the main script can be invoked from anywhere.
Fix AngelScriptAPI.h header generation.

- Define int64 and uint64 and redefine the existing type to closer match AngelScript documentation.
- Replace occurances of ?& (any reference) to void*.
Update documentation on Using Urho3D library.
Removed the mechanism of binary-serializing resource name hashes instead of resource names. This is to allow correct resource loading from binary scene files on platforms that cannot iterate the resources in the application installation (eg. Android). This also affects networking, downside is increased network payload size when resource attributes are transferred. All binary scenes saved with old Urho versions are also invalidated.
Use WeakPtr<RefCounted> consistently for the script WeakHandle type.
Refresh the generated scripting API docs.
Fixed CompileAllShaders.bat compiling SM2 shaders into SM3 directory.
Fix template code error.
Configure and install Urho3D.pc file for pkg-config tool.

This is useful for Urho3D library user via SDK installation without having CMake installed.
Fix incorrect include dirs in the Urho3D.pc file.

Also:
- Change the CMake module installation destination to use small letter case.
- Update documentation on pkg-config invocation examples.
Avoid hardcoding of include dirs in the Urho3D.pc.in input file.

Also revert decision to use smaller letter case cmake destination directory in previous commit :).
Allow setting AnimationState bone weights recursively. Added GetAnimationState() to public API of AnimationController.
Fix Urho3D.pc file for Windows and Raspberry Pi platforms.

Document cross-compiling example using pkg-config for Raspberry Pi platform.
Disable Urho3D.pc file generation for Android and iOS platform.
Check for compound shape with zero child shapes to prevent Bullet assert. Closes #47.
Fix SDK destination installation path for Windows platform.

It appears CMake has automatically prepended "Urho3D" to built-in CMAKE_INSTALL_PREFIX variable, so we don't need to prefix the path one more time. Also in the commits:
- Fix documentation on CMake module search path for Windows platform.
- Unified SDK destination installation for Windows and non-Windows platforms.
- Replace global include directories to SDL and export header to locally scoped include directories.
- Enhance Urho3D.pc generation to also provide additional compiler flags for DEBUG/RELEASE/RELWITHDEBINFO as comments/references.
Moved SDL header include dir to 'Engine' scope as it is being referenced by a few Engine sub-directories and not just Graphics.
Improved resource unloading. Make it possible to unload all resource types by partial name at once. Editor unloads unnecessary resources after scene load or clear. Add weak ref check to all resource unloading to avoid shader programs being left without their parent shader.
Add int versions of Max, Min & Clamp to the AngelScript API.
Force elements in layout to left/top alignment, warn if has different alignment. Closes #34. Implement editor accelerator key texts a bit differently as the right alignment in a layout -hack can no longer be relied upon.