added support for radius for three vertices of triangle
added an upper limit on radius in triangle component
added polymorphic constructor for trianglepath.
It can now take three type of arguments for vertex radius.
- No value. Hence no vertex radius
- A single value which will be radius of all vertices
- Three values which correspond to radius of each vertex
rewrote the conditions to calculate border radius of triangle

Greater flexibility has been provided.
- User can input two radii as well. Third one will be taken as zero.
removed feature implementation of Group.clear() from this branch
fixes indentation issue
Merge pull request #23 from Supreetpal/feature/triangle-component

Feature/triangle component added to the list of components.