NF: multiple new things and enhancements

NF: Choices
ENH: Choice boxes for GUI
NF: _get_methods_byname
NF: splash screen
ENH: auto nice layout
ENH: launches exps as new processes
cleanup
RF: variable names to lowercase
ENH: GaborJet simple cell raise exception
ENH: unstacking comes from plot
ADD: splash screen
BF: line_plot doesn't do xticks by itself anymore

ENH: show() does tight_layout()
some general cleanup
RF: multiple changes

NF: instructions can be in HTML or reST format
RF: _Common removed
ENH: data file name, random seed for tasks
NF: Event for making events
RF: moved outside Experiment: latin_square, weighted_choice, make_para
RF: before_ and after: exp, task, block
NF: Datafile for data file handling
RF: wait_for_response -> wait_until_response
DOCS: create plots on the fly
DOCS: updated and extended for version 0.5
DEMOS: new demos added, old updated

twotasks, staircase, perclearn
ENH: prepared info for version 0.5