[pgrouting-dev] Doc for Legacy file

[Stephen Woodbridge]

Hi Daniel,

I reviewed the src/common/sql/pgrouting_legacy.sql today and:

1. added the shooting_star function in addition to the shooting_star 
wrapper that was already there. Both of these function raise and 
exception noting that this functionality has been drop in 2.0 and user 
need to migrate to pgr_trsp() function.

2. created src/common/doc/legacy.rst which needs to be linked into the 
documentation somewhere. My goals for this page are:
   a. Explain why these functions are gone from the release
   b. make it clear that these functions are not support and not tested
   c. Explain that we are temporarily providing this unsupported file in 
the hope it might be useful
   d. list without explanation what functions are in the file as kind of 
a quick reference

Feel free to make changes. This closes issue #100

Thanks,
   -Steve