Docs: Replace references to raylib develop branch

Found by grepping for '(blob|tree)/develop'.  See #443 for more information.

CONTRIBUTING.md

@@ -34,18 +34,6 @@ Source code is extensively commented for that purpose, raylib primary learning m
 
  > learn by reading code and examples
 
-
-### Using raylib develop branch
-
-raylib [master branch](https://github.com/raysan5/raylib) contains the latest raylib release but all 
-the future work is always done on [develop branch](https://github.com/raysan5/raylib/tree/develop), 
-it's far ahead of master and I try to keep it always stable with latest library changes.
-
-Please, if issuing a bug or sending a pull-request, verify that you're using develop branch.
-
-Note that while using develop branch predefined Notepad++ building scripts could not work, in that case,
-use provided [Makefile](https://github.com/raysan5/raylib/blob/develop/src/Makefile) or [CMake](https://github.com/raysan5/raylib/blob/develop/src/CMakeLists.txt) building systems.
-
 For detailed information on building raylib and examples, please check [raylib Wiki](https://github.com/raysan5/raylib/wiki).
 
 ### Opening new Issues
@@ -62,8 +50,6 @@ To open new issue for raylib (bug, enhancement, discussion...), just try to foll
 
 ### Sending a Pull-Request
 
-To send a pull-request, first of all, make sure you're sending it to [develop branch](https://github.com/raysan5/raylib/tree/develop). Here are some other rules:
-
  - Make sure the PR description clearly describes the problem and solution. Include the relevant issue number if applicable.
  - Don't send big pull-requests (lots of changelists), they are difficult to review. It's better to send small pull-request, one at a time.
  - Verify that changes don't break the build (at least on Windows platform). As many platforms where you can test it, the better, but don't worry

LICENSE.md

@@ -27,7 +27,7 @@ applications, and to alter it and redistribute it freely, subject to the followi
 fonts
 ------
 
-The following fonts [provided with raylib](https://github.com/raysan5/raylib/tree/develop/examples/text/resources/fonts) are free to use (freeware) and have been designed by the following people:
+The following fonts [provided with raylib](https://github.com/raysan5/raylib/tree/master/examples/text/resources/fonts) are free to use (freeware) and have been designed by the following people:
 
  * Alpha Beta - Brian Kent (AEnigma)
  * Setback - Brian Kent (AEnigma)
@@ -41,9 +41,9 @@ The following fonts [provided with raylib](https://github.com/raysan5/raylib/tre
 2d art
 ------
 
-[scarfy spritesheet](https://github.com/raysan5/raylib/blob/develop/examples/textures/resources/scarfy.png) and [fudesumi image](https://github.com/raysan5/raylib/blob/develop/examples/textures/resources/fudesumi.png) have been created by [Eiden Marsal](https://www.artstation.com/artist/marshall_z) and licensed as [Creative Commons Attribution-NonCommercial 3.0](https://creativecommons.org/licenses/by-nc/3.0/legalcode)
+[scarfy spritesheet](https://github.com/raysan5/raylib/blob/master/examples/textures/resources/scarfy.png) and [fudesumi image](https://github.com/raysan5/raylib/blob/master/examples/textures/resources/fudesumi.png) have been created by [Eiden Marsal](https://www.artstation.com/artist/marshall_z) and licensed as [Creative Commons Attribution-NonCommercial 3.0](https://creativecommons.org/licenses/by-nc/3.0/legalcode)
 
 3d models
 ---------
 
-[dwarf 3d model and textures](https://github.com/raysan5/raylib/tree/develop/examples/models/resources/model) have been created by David Moreno and licensed as [Creative Commons Attribution-NonCommercial 3.0](https://creativecommons.org/licenses/by-nc/3.0/legalcode)
+[dwarf 3d model and textures](https://github.com/raysan5/raylib/tree/master/examples/models/resources/model) have been created by David Moreno and licensed as [Creative Commons Attribution-NonCommercial 3.0](https://creativecommons.org/licenses/by-nc/3.0/legalcode)

ROADMAP.md

@@ -4,7 +4,7 @@ roadmap
 Current version of raylib is complete and functional but there is still a lot of room for improvement.
 Here it is a wish-list with features and ideas to improve the library.
 
-Note that [raylib source code](https://github.com/raysan5/raylib/tree/develop/src) has some *TODO* marks around code with pending things to review and improve. Check [GitHub Issues](https://github.com/raysan5/raylib/issues) for further details!
+Note that [raylib source code](https://github.com/raysan5/raylib/tree/master/src) has some *TODO* marks around code with pending things to review and improve. Check [GitHub Issues](https://github.com/raysan5/raylib/issues) for further details!
 
 **raylib 1.x**
  - [ ] Basic GPU stats sytem (memory, draws, time...)