Bug fixes and new controls

We have included advanced control options, option to control phosphate and cation charges. Also included time scale slider to control the speed of simulation. 

The bug is fixed where a cation could not be attracted to DNA strand.

The bug fixed where added DNAs could be plunged into already existing ones. I used Physics2D.CapsuleOverlap().

Now DNA can form hairpin due to increased angle limit between nucleotides.

Final addition has been links to aoiti website, youtube channel, twitter etc.