ENH: extend support for EPANET conversion to all valve types

[fletchapin]

Use Case

Currently only the only valve type supported in epyt_utils is the pressure release valve (or PRV).

Solution

EPANET has the full list of valve types on their website:

• Pressure Reducing Valve (PRV)
• Pressure Sustaining Valve (PSV)
• Pressure Breaker Valve (PBV)
• Flow Control Valve (FCV)
• Throttle Control Valve (TCV)
• General Purpose Valve (GPV)

Alternatives

Currently a user would have to code all valves as generic Valve objects, which leads to information loss.