Merging ATSP solution GIST by dapotts

https://gist.github.com/dapotts/6133259
https://github.com/pgRouting/pgrouting/issues/167

1. Non continuous number ranges in the pgr_tsp. Usage is select seq,id
from pgr_mktspret('select source,target,cost from edge5' ,xx); where xx
is any node, which does have to be in the range 1-N
2. A function for checking if your distance matrix is valid
pgr_checktsparray, takes an distance matrix and check that there are
enough values, only zeros are in the leading diagnonal, The value i,j is
the same as j,i
3. A method for resolving the Asymmetric salesman problem. Process a a
distance matrix where the cost of A-B is not the same as B-A
Merge branch 'develop' of https://github.com/ZupoLlask/pgrouting into develop