Custom implementation that returns -1 if it fails (no negative values supported)

...while using a RenderTexture combined with 3d mode

REDESIGNED: rlLoadRenderTexture()
ADDED: rlRenderTextureAttach()
ADDED: rlRenderTextureComplete()

Probably uncomplete, not tested yet...

Added DrawTextRecEx()

GGJ2019 game

Fix clang++ compilation errors

Fix font cannot be narrowed to type 'int'

Getting the following strict error....

```
src/text.c:117:105: error: constant expression evaluates to 2398692640 which
      cannot be narrowed to type 'int' [-Wc++11-narrowing]
...0x00000000, 0x00000000, 0x00200020, 0x0001b000, 0x00000000, 0x00000000, 0x8ef92520, 0x00020a00...
                                                                             ^~~~~~~~~~
```

Switching it to an unsigned int fixes it.

clang was complaining about the type conversions. For example...
```
node_modules/raylib-src/src/core.c:1888:15: error: cannot initialize a variable of type 'char *' with an
      rvalue of type 'void *'
        char *cmd = calloc(strlen(url) + 10, sizeof(char));
              ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Remove libraylib.a

They could be useful for some people...

Reorganizing logging

cmake: fix resource preloading for web examples

No examples built for the Web platform functioned properly due to lack
of resources in the virtual file system provided by emscripten.

This patch addresses this problem by adding
'--preload-file local_path/resources@resources' emcc option to link
flags whenever necessary.

The default memory limit for emscripten applications is 16 mergabytes,
which might be to little for some examples, especially given that the
resources are also included in that limit.

Normally, using this option disables some asm.js optimizations, but
there's no such cost for WebAssembly.

$prefix/lib isn't in pc_path on Fedora 28:

    [root@fedora-28 ~]# pkg-config --variable=pc_path pkg-config
    /usr/lib64/pkgconfig:/usr/share/pkgconfig

This has the effect that the pkg-config file is written to the
correct location but pkg-config --libs raylib doesn't output
the correct library path. This fixes this problem by substituting
the directory names into the .pc, same as we do with the CMakeLists.txt
since #518.

This issue popped up during the automated test of the Perl bindings:
    https://github.com/athreef/Alien-raylib/issues/3

Remove `raylib-rust`

Function provisional renaming... that's not the end of this issue...

When capturing framebuffer, if some element with transparency has been drawn, it retrieves that data... it could be a bit annoying in some situations because we could expect color compositing with background color... It depends on the situation and our needs... but most of the time we don't want that transparency on screenshots.

Trace log failing on other