Created repository for spoke length calculator. This is mainly for ease
of distribution (ie. publishing on github), but it is also pragmatic should
I (or anyone else) want to add more features, like a GUI.

As of this commit, the program works fine, but doesn't have an install
script, which would be quite useful.
Bugfix to correct the spoke length formula implementation. Previously, the
angle parameter to the cosine rule was calculated as 2*pi... which is
incorrect, it should be 4*pi.

I discovered this bug the hard way :( Bought spokes, went to build the
wheel and found out the spokes are the wrong length. Well that's
embarassing!
Merge branch 'master' of github.com:pkill-9/spoke

Initialised remote repository on github, with GPL licence and readme,
which are being merged into my development repository.