Code cleanup

1. Added a standard header to each code module and removed obsolete comments.
2. Re-named several of the sub-structs in the project struct and re-arranged some of their contents.
3. Re-named _defaultModel to _defaultProject.
4. Removed the need to call EN_createproject and EN_deleteproject when working with the default project.
5. Made X & Y coords. part of Snode properties instead of a separate struct.
6. Moved the non-API functions in epanet.c into a new module named project.c.
7. Re-factored the quality module so that it uses the same nodal adjacency lists as the hydraulics solver.
8. Re-factored the sparse matrix module (smatrix.c) to be more memory efficient.
9. Restricted line lengths to < 90 columns.
10. Grouped the placement of functions in EPANET2.H and EPANET.C by category.

src/mempool.h

@@ -1,9 +1,14 @@
 /*
-**  mempool.h
-**
-**  Header for mempool.c
-**
-**  A simple pooled memory allocator
+ ******************************************************************************
+ Project:      OWA EPANET
+ Version:      2.2
+ Module:       mempool.h
+ Description:  header for a simple pooled memory allocator
+ Authors:      see AUTHORS
+ Copyright:    see AUTHORS
+ License:      see LICENSE
+ Last Updated: 11/27/2018
+ ******************************************************************************
 */
 
 #ifndef MEMPOOL_H