cosmetic:  added new commits to README and renamed it Changelog; split out the old README.txt (non-Changelog part)

JobFactory uses $overriding_hash to create jobs/rows from input_id_template; 'input_id' parameter deprecated; standaloneJob supports templates.

Substitution machinery now supports an extra $overriding_hash that contains parameters with higher precedence than the whole of param() structure

fixed several problems with parameter substitution and detection of undefs; added param_required() and param_is_defined()

In case no -logic_name/-analysis_id was supplied, show the list of analyses that have no incoming dataflow (and so are candidates for seeding)

diagram improvement: (1) no more "empty boxes" and (2) tables dataflown from a box are shown in their boxes

Added coloured barchart display option and jobs/data display option (no big data checks, use with care on small examples).
'Pad' is now configurable from JSON.
Beware: JSON config options have moved around!