Added cmake support (#11)

* Update README.md

* added submodules

* moved submodules to release tag

* fix include for fixed width integer

* added cmake support and build instruction

* Update README.md

* fix cmake links

* upd CMakeLists.txt

.gitmodules

@@ -0,0 +1,6 @@
+[submodule "libs/glm"]
+	path = libs/glm
+	url = https://github.com/g-truc/glm.git
+[submodule "libs/glfw"]
+	path = libs/glfw
+	url = https://github.com/glfw/glfw.git