Make the x and y error bars in plots accessible in the record command / function

[Christian Speckner]

All said in description.

[kilian]

r2633 has this, plus many improvements/changes to the analysis and plotting facilities. The idea is to make the commands more self-explaining, while merging in cnspeckn's additions.

At user level:

• The 'plot' command takes no arguments (bounds) anymore. Bounds can be set in the options by x_min, x_max, y_min, y_max. If these are unknown, GAMELAN will take care of the bounds.
• The previous 'write_analysis' command is now called 'compile_analysis'. The filename is no longer $analysis_filename but $out_file. $out_file should contain the extension (e.g. $out_file = "foo.dat"). The value of $out_file is also used by open, close, and print/printf.
• The previous 'write_analysis_data' command is now called 'write_analysis'. There is no suffix (which was default/csv/custom), but an option ?out_custom. The 'histogram_writer' and 'plot_writer' macros are honored if ?out_custom=true.
• The 'record' command and function can take up to four arguments. Their use depends on the analysis object. For observables and histograms, one argument. For plots, the arguments are x, y, yerr, xerr. The latter two are optional.
• There are many more options to histograms and plots, and a new analysis object type 'graph' which allows to combine several histograms/plots in one graph.

Part of this is already documented in the updated manual. The new graphics options are not yet documented, to be done asap.