Added support for single header implementation and also inline functions
support

- Added simple ray-sphere collision detection.
- Added extra function with extended parameters to obtain collision
point vector.
- Fixed bounding box calculations init values (were causing compiling
errors).

standalone raymath

look over for errors

Moved building information to raylib github Wiki page

Reviewed vertex type variables

World to screen conversion and little review

- Added function WorldToScreen(...).
- Added world to screen example.
- Review GetMouseRay() comment.
- Removed deprecated lighting functions from raylib header.

Simplified for the user (more intuitive and clear)
Removed lighting module dependency

... transparent elements

Fixed small glitch on zoom-in

It seems that now works. Tested all free camera features with some
directions and positions and no unexpected behaviours detected. I don't
know if those lines are really indispensable.

Implemented ray trace from mouse position

- Added CheckCollisionRayBox() function.
- Updated and improved core 3d picking example (currently working as
expected).

- Fixed GetMouseRay() function.
- rlglUnproject() unused.

Fixed Android bug and added physic buttons inputs

- Fixed Android locking screen bug. OnDestroy() was called when locking
screen.
- Power button input must be handled by OS.
- AndroidManifest.xml is affected by configChanges="screenSize".
- Updated library header for android template.

- Added functions for detect when pressed, during down and when
released.
- Added defines for back, menu, volume up and down button numbers.

Two new functions added to save/load values as binary data:
- StorageSaveValue()
- StorageLoadValue()

Improved lighting and physac engine modules and added new example

New physics example to see AddForceAtPosition() behaviour applied to 5
rigidbodies.

- Improved physics calculations.
- Added AddForceAtPosition function (added to all enabled rigidbodies).
- Updated raylib header.