Split README.developer into two: README.developer and README.dissector. All the

Split README.developer into two: README.developer and README.dissector. All the
documentation specific to dissectors should now live in README.dissector - what
remains in README.developer should be useful to anybody coding on Wireshark
regardless of if you're working on the GUI, wiretap, dissectors, etc.

This first pass I did a fairly dumb split of copy-pasting relevant chunks from
one file to the other. There are probably fragments that aren't in the right
file anymore, so cleanup welcome.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@50092 f5534014-38df-0310-8fa8-9805f1628bb7