Updates happen via git with no regular release schedule or versioning.
However, I will bump up the GNUPLOT_IOSTREAM_VERSION macro whenever
something major changes (but note that prior to version 2 this macro is not
defined).

Version 2:
	* Major rewrite.
	* Nearly every combination of container and tuple types is supported.
	* Now you should use send1d() and send2d() rather than just send().
	* When the Gnuplot object is constructed with no arguments, an attempt is made to determine
	  the best gnuplot command and arguments for your operating system.

Version 1:
	* Original version.
	* The GNUPLOT_IOSTREAM_VERSION macro is not defined prior to version 2.