update license

LICENSE

@@ -19,3 +19,28 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+-
+
+This library [initially] used some [piece of] implementations
+(may include codes) from these open source projects:
+
+1. Affine Transforms
+The original glm repo (g-truc), url: https://github.com/g-truc/glm
+
+LICENSE[S]:
+  The Happy Bunny License (Modified MIT License)
+  The MIT License
+  Copyright (c) 2005 - 2016 G-Truc Creation
+
+FULL LICENSE: https://github.com/g-truc/glm/blob/master/copying.txt
+
+2. Quaternions
+Anton's OpenGL 4 Tutorials book source code:
+
+LICENSE:
+  OpenGL 4 Example Code.
+  Accompanies written series "Anton's OpenGL 4 Tutorials"
+  Email: anton at antongerdelan dot net
+  First version 27 Jan 2014
+  Copyright Dr Anton Gerdelan, Trinity College Dublin, Ireland.