add initial inlet control api functions

[karosc]

This PR adds some basic api functionality for inlets of street links in SWMM 5.2.3.

3 new api functions:

• swmm_getInletParam: get parameters assigned to inlets of a given street link. The parameters are only those assigned to the inlets of a given street, NOT the inlets designs upon which they are based.
• swmm_setInletParam: set parameters assigned to inlets of a given street link. Currently only clog factor and flow limit are supported and can be set during a simulation to approximate progressive inlet clogging.
• swmm_getInletResult: result data associated with inlets that are otherwise only internal to the SWMM model. These may or may not be useful for modelers......TBD
  • flow capture: the captured flow rate by the inlet
  • back flow: the back flow rate from the capture node of an inlet
  • back flow ratio: inlet backflow / capture node overflow

[bemcdonnell]

These new entry points look really nice.. I think they will be pretty useful!