* No longer needs an X connection to render. This also vastly increases
performance.
* If too many configuration values are plotted, a key with color=column1,
line=column2, marker=column3 etc is not created. Instead, each combination
of values is given its own line/color/marker style and plotted, and each
line has an entry in the key. Ugly, but better than nothing.

This creates csvs which have merged the lines which only differ by variables
whose values are numbers (e.g. 'wss', 'number of tasks', or 'duration',
but not 'scheduler').

For example, consider a csv which is tracking the change in working set sizes.
There are 3 different experiment configurations per WSS, one with 12 tasks,
one for 14, and another for 16. Without --collapse, a seperate csv
(and line to plot in plot_exps.py) will be created for each of the 12, 14, and
16 configurations. With --collapse, a single csv (and a single line plotted
by plot_exps.py) will be created which averages the values of 12, 14, and 16
tasks for each WSS.

This is very useful for noticing trends or presenting overhead bar charts
or other examples in papers.

With no arguments, all scripts first try to load the current directory. If the
current directory has no data, the scripts search for the output of the previous
scripts in the toolchain, e.g. parse_exps.py loads run-data/*, created by
run_exps.py.

This commit also switched messages to stderr where they belong, and adds in
missing lock and unlock overheads.