    Plot the convergence of JDFTx from its output files using gnuplot. Usage:

            plotConvergence <file1> <file2> ...

    If multiple output files are specified, they will be plotted alongside.

    The behavior is controlled by several environment variables:
            nLines      Plot the final $nLines iterations (default: 1000)
            skipLines   Ignore the first $skipLines iterations (default: 0)
            iterType    Select iteration type: Elec (default), Ionic, Fluid etc.
            logTarget   Plot energy difference from $logTarget on a log axis.
            xAxis       "iter" (default) or "time" to plot versus iteration count or run time
            term        GNUPLOT terminal with options (default "wxt enhanced dashed", or "dumb" without X)
            out         GNUPLOT output file; match this with term (default None)