Takes as input a file defining the execution of a number of chat processes,
runs those processes, and saves the output in a file, separated into the output
for each process.

The output file by default is test.out.txt.  You can specify a different name
on the command line with --outfile or -o.

Input file format:
First takes any number of global directives. No global directives are defined yet.

Then it expects a section starting with [name] on a line, followed by
execution directives.  For each of these sections, one './chat' process is
launched and given the input defined by the execution directives.  Note that
name should be unique. After all execution directives are finished, the process
will be killed.  The checker will run until all processes have reached this
state.

Execution directives are:
wait num_seconds(float)
send message
crash

For example, for the 0th process:
[0]
wait 1.0
send "hi"
wait 8.0
crash