Corrected bug on ImageDrawRectangleLines()

REVIEWED: ImageDrawRectangle()
ADDED: ImageDrawRectangleLines()

By default, internal white texture was used to draw most of the shapes; some time ago, support for white font character from default internal font was added. That way, all basic drawing (shapes, text) could be performed without a texture change and in a single drawing pass.

Now, we move a step further and we allow configuring the texture (and rectangle) used to do the shapes drawing.

text:     IsEqualText() -WIP-
audio:  SaveWAV()
audio:  ExportWaveAsCode()
textures:  ExportImageAsCode()

RENAME: GetLastWriteTime() to GetFileModTime()

- Added a function to get the last write time of a file. I used this so I can reload files or resources if the time since they were last loaded changes.

The prototype of GenImageFontAtlas() in the main raylib.h header has a set of swapped parameter names.
Going through the usage of the function within raylib itself, it appears as if the correct order is:
1) charsCount
2) fontSize

However, it's exposed to the world as the other way around, which may cause some major confusion.

REVIEW: Reorganized global variables for consistency
ADDED: GetWindowHandle() to get native window handle
ADDED: GetDirectoryFiles() to get files list for a DIR

Previously, if <raylib.h> was #included prior to another header that
defined bool, the compilation would fail.
This is e.g. the case for <perl.h> and <objc/objc.h> which both fall
back to the <stdbool.h> if C99 is available.

The following commit includes <objc/objc.h> in src/core.c, which causes
the same problem.

Avoid this by checking for C99 bool like we already do for C++'s.

- Using same idea as SetWindowMonitor to take in a index with 0 being the primary monitor.

- Fixed tabs used instead of 4 spaces

- Get number of monitors
- Get size, physical size and name of primary monitor. Could pass monitor id instead not sure.

REVIEWED: ExportImage()
REVIEWED: ExportMesh()
ADDED: ExportWave()
REMOVED: Internal funcs: SavePNG(), SaveBMP()

NOTE: These changes break the API (parameters order)

Useful for bitmaps pixelated fonts where anti-aliasing is not desired!
Change also enables additional font generation mechanisms in a future (cleartype, hinting...).

Added support form vertical and horizontal 3-patches.
Corrected the distortion caused when destRec size is smaller than 4x4. Now even 1x10 or 0x0 sizes are drawn correctly.

Added NinePatch struc definition and function prototype.

Still a work in progress but it already works...
Current riqm API could be simplified...

Vector4 -> Quaternion
Texture2D -> Texture
RenderTexture2D -> RenderTexture
Camera3D -> Camera
SpriteFont -> Font

Note for me: Replace All is NOT your friend...

Library consistency rename... yes, I know, it breaks the API...

Added: data to CharInfo struct
Added: LoadFontData()
Added: GenImageFontAtlas()
Removed: LoadFontEx()
Removed: LoadTTF() [internal]
Some code tweaks

Reviewed: GetImageData()
Reviewed: ImageFormat()