Add EN_PRESS_UNITS to EN_getoption & EN_setoption

doc/input-file.dox

@@ -279,6 +279,7 @@ __Formats:__
 <table style = "border: 0px solid black">
 <tr><td><B>UNITS</B></td><td><B>CFS / GPM / MGD / IMGD / AFD /</B></td></tr>
 <tr><td>  </td><td><B>LPS / LPM / MLD / CMS / CMH / CMD</B></td></tr>
+<tr><td><B>PRESSURE</B></td><td><B>PSI / KPA / METERS</B></td></tr>
 <tr><td><B>HEADLOSS</B></td><td><B>H-W / D-W / C-M</B></td></tr>
 <tr><td><B>HYDRAULICS</B></td><td><B>USE / SAVE </B><I>&nbsp;filename</I></td></tr>
 <tr><td><B>VISCOSITY</B></td><td><I>value</I></td></tr>
@@ -321,6 +322,8 @@ __Definitions:__
 
 For <b>CFS, GPM, MGD, IMGD</b>, and <b>AFD</b> other input quantities are expressed in US Customary Units. If flow units are in liters or cubic meters then Metric Units must be used for all other input quantities as well. (See the @ref Units topic). The default flow units are \b GPM.
 
+\b PRESSURE sets the units in which pressure is expressed, for networks using metric units, as determined by the \b UNITS option, the choices are: (\b KPA), or (\b METERS). For networks using US Customary Units, you can only use (\b PSI).
+
 \b HEADLOSS selects a formula to use for computing head loss for flow through a pipe. The choices are the Hazen-Williams (\b H-W ), Darcy-Weisbach (\b D-W ), or Chezy-Manning (\b C-M ) formulas. The default is \b H-W.
 
 The \b HYDRAULICS option allows you to either <B>SAVE</B> the current hydraulics solution to a file or \b USE a previously saved hydraulics solution. This is useful when studying factors that only affect water quality behavior.

doc/modules.dox

@@ -289,6 +289,7 @@ These are the toolkit's enumerated types whose members are used as function argu
 \enum EN_TimeParameter
 \enum EN_Option
 \enum EN_FlowUnits
+\enum EN_PressUnits
 \enum EN_DemandModel
 \enum EN_MixingModel
 \enum EN_StatisticType

doc/toolkit-units.dox

@@ -25,7 +25,7 @@ The toolkit can use data expressed in either US Customary of SI Metric units. A
 |Length          | feet                    | meters                    |
 |Minor Loss Coeff. | unitless              | unitless                  |
 |Power             | horsepower            | kwatts                    |
-|Pressure          | psi                   | meters                    |
+|Pressure          | psi                   | meters or kPa             |
 |Reaction Coeff. (Bulk) | 1/day (1st-order)| 1/day (1st-order)         |
 |Reaction Coeff. (Wall) | mass/sq-ft/day (0-order) | mass/sq-m/day (0-order) |
 |                       | ft/day (1st-order)       | meters/day (1st-order)  |