- objectRegistry gets a rename() that also adjusts the dbDir
- cloud reworked to use static variables subInstance and defaultName.
This avoids writing "lagrangian" everywhere
string fixes
- avoid masking of std::string::replace in string.H
- avoid old strstream in PV3FoamReader
- uniform use of reinterpret_cast<foo*>(0) instead of
reinterpret_cast<foo*>(NULL)
- make all static null() members inline since they are really only a cast:
"*reinterpret_cast<foo*>(0)"