Some tools now output sets at the pointsInstance (if relating to geometry),
some at the facesInstance (if relating to topology).
So when loading them we now search for them from current time down
to facesInstance. They cannot be beyond facesInstance.
Adapted Time::findInstance to take optional limiting instance. Adapted
topoSet to use this. Adapted all uses of IOobjectList on sets to do the
same.
- removed the previously added fileName type(), isDir(), isFile() methods.
- added optional bool parameter to isFile() function to explicitly
enable/disable the check for gzip files.
- fixed minor bugginess where the default usage of isFile() would result in
false positive matches.
- be slightly more stringent and use isDir() and isFile() instead of
exists() function when we actually know the expected type.
- can use 'XX.empty()' instead of 'XX.size() == 0', 'XX.size() < 1' or
'XX.size() <= 0' or for simpler coding.
It also has the same number of characters as '!XX.size()' and /might/ be
more readable
- many size checking had 'XX.size() > 0', 'XX.size() != 0', or 'XX.size() >= 1'
when a simple 'XX.size()' suffices
