Fixed installation so that this "gui" part can be installed with
standard autoconf techniques: configure, make all, make install
The "gui" library is loaded via "package require RapptureGUI"
Added C code for Rappture::rlimit, to support limits on CPU time
and file sizes. Default limits are 15 mins of CPU and 1MB for
each file. These can be overridden in tool.xml by using
<tool><limits><cputime> and <tool><limits><filesize>.
Added C code for Rappture::rusage, so we can collect resource
usage for all child processes. Each Simulation now reports
a line of usage to stderr as follows: