[boost] pqs physical quantities library version 3_0_4 in the vault

Version 3_0_4 of pqs is in Physical Quantities Units directory in the vault. The major change is that pqs_3_0_4 has been tested on various compilers including gcc3.2, gcc4.01, VC7.1, VC8 where previously it only worked on VC7.1. Still no real documentation though. regards Andy Little