This commit removes the #ifdef _DEBUG statements at the top of all source code files per issue #482. It also updates the doc files to stress that the speedup observed for hydraulic analysis with the MMD node re-ordering method only applies to single period runs.
Adds an output argument to EN_addnode and EN_addlink that returns the index of the newly added object.
Also refactors the validity check on object ID names.
The newly added `gettitle` and `settitle` functions were moved from the Reporting Functions section to the Project (formerly System) Functions section of epanet2.c and epanet.c.
