- moves the exception definitions to a new header (IMP/exception). log.h
includes this so no other headers have to change directly. As a side
effect, exceptions are no longer exported to python. We can revert this
easily enough
- adds a IMP::Exception base class for all exceptions which stores a
string and implements what() so the the string is passed to python
- all exceptions (except ErrorException) now require a string (or const
char*) in their constructor so that python gets the message
This is of course the obvious solution (throwing the string away before
made the Python interface a bit ugly) but I hadn't done it that way
myself because my understanding is that this isn't valid C++. See the
log message for this commit:
Our current set of compilers seems to accept this code though.
As a side note, don't we want IMPDLLEXPORT on Linear? As it is, you end
up with two separate copies of the class, on in libimp and one in _IMP.
Not catastrophic, but probably not what we want. Such a problem appears
to be catastrophic with exceptions :-)
I removed it, because MSVC wouldn't compile with it in, precisely
because there _isn't_ a copy of the class in libimp - it is never
instantiated there. But it is possible that MSVC tricked me again with
its cryptic error messages and built-in bugs.