Fix: reset s_hRbTotal(Force|Torque) also if subdomain is empty
Fix in network float reduction

Was performed in place without the appropriate MPI option
problem_select.h should not exist either
Whitespace cleanup
Convert most VTKWriter to ofstream

The most important aspect of this conversion is that by setting
exceptions on failbit and badbit, we can get an exception to be thrown
automatically on failure, without having to check for failure at every
single write.
Refactor open_data_file to share it with all writers
Convert CustomTextWriter to new ofstream system
Convert TextWriter to new ofstream system
Convert VTKLegacyWriter to new ofstream system
Get rid of all C-style output in writers
VTK writers: ensure VTU index is always valid
VTKWriter: always save flag, conditionally save fluid and object

Also reduce data sizes to UInt8 wherever possible.
Sample pvpython script that shows the bounding box of the fluid

The script can be of use in itself, but it's most importantly an example
of how to use pvpython (the ParaView python interface) to extract data
from a simulation without having to mess around with ParaView's UI.
Fluid/object number should be uchar, not ushort
getNeibIndex: use const& instead of const

It's generally more efficient to pass non-POD const parameters by ref,
although for inlined functions it won't make much of a difference.
surface detection fix for homogenenous precision

Also throw in some const-ification.
Writer: copy-paste error
Gage fix for homogeneous precision
VTKWriter: put NaN gages at the world bottom