bugfix: schemas/vegbien.sql: locationevent: locationevent__pull_forward_from_parent() trigger: only pull forward the location_id when there is a stratum_id, so that empty locationevents that should be auto-forwarded are not unintentionally made valid by populating the location_id field (which causes a check constraint to become satisfied, and prevents auto-forwarding from working). this fixes a bug in some datasources' automated tests, such as `make inputs/SALVIAS/plotObservations/test`.

lib/sql_io.py: put_table(): default param: documented that this will be used for all missing rows, regardless of which error caused them not to be inserted. this means that auto-forwarding (wiki.vegpath.org/Auto-forwarding) can be used with any type of constraint violation, not just NOT NULL constraints (which it is typically used with).

/Makefile: mk_db: config/users.sql: unset ON_ERROR_STOP so user-exists errors don't prevent further user-adds

planning/timeline/timeline.2013.xls: updated for progress

bugfix: schemas/vegbien.sql: analytical_stem_view: plot__collectors: to include plot__collectors for nested stratum events, need to calculate the locationevent__contributors__array() for the locationevent and parent_event separately, and then COALESCE those, instead of just running locationevent__contributors__array() once on the COALESCE of the two IDs

bugfix: schemas/vegbien.sql: locationevent: added pull-forward trigger to populate location_id from the parent event. a pull-forward trigger must be used for this (not a COALESCE in analytical_stem_view) because the locationevent cannot even be found by analytical_stem_view if it does not have an associated location.

schemas/VegCore/ERD/VegCore.ERD.mwb: source: added required url field, which points to the source data and uniquely identifies the source. note that this differs from the id, which is a self-refential pkey (as described at wiki.vegpath.org/Web_interface#Clickable-fkeys).

schemas/VegCore/ERD/VegCore.ERD.mwb: fixed lines

schemas/VegCore/ERD/VegCore.ERD.mwb: regenerated exports and udpated image map

schemas/VegCore/ERD/VegCore.ERD.mwb: source: removed canon, because this would create too much complexity as a result of having multiple copies of the same source with different names. instead, source names will be scrubbed upon insert so that the row always contains the most accurate data, and there is only one copy of each source. this scrubbing may use the assistance of a thesaurus table w/ standard abbreviations, etc.