Add accidentally removed README file.

README.md

+# FlowSim
+
+The FlowSim application allows its user to draw shapes and map them onto an interactive fluid dynamics simulation.
+
+FlowSim was developed as a Bachelor thesis to study test driven development.
+
+
+
+## Structure
+
+The following image represents a simplified overview over FlowSim's internal structure
+![][overview]
+
+[overview]: https://github.com/SvenMarcus/FlowSim/blob/master/overview.png
+