Strange unit conversions

[jukka.lind at kolumbus.fi]

Pressure unit conversions in dive.h seem strange to me.
What is the meaning of  "0.5" in psi_to_mba and int to_PS ? If they're there to minimize rounding error when moving from integer to real, shouldn't they be before the multiplying ?
The error at normal tank pressures is minimal and at 1 bar just about 3 %, but anyhow.

 191 static inline unsigned long psi_to_mbar(double psi)
 192 {
 193         return psi_to_bar(psi)*1000 + 0.5;
 194 }
 195 
 196 static inline int to_PSI(pressure_t pressure)
 197 {
 198         return pressure.mbar * 0.0145037738 + 0.5;
 199 }


Sorry I haven't the "development environment" set up yet.
Signed-off-by: Jukka Lind <lino at iki.fi>