mappings/VegX-VegBIEN.stems.csv: Sort the plantobservation.sourceaccessioncode/specimenreplicate.sourceaccessioncode mapping with the other _ifs so the adjacent node merging works properly and it gets created before _ignore removes voucherType

mappings/VegX-VegBIEN.stems.csv: Also map plantobservation.sourceaccessioncode to specimenreplicate.sourceaccessioncode so specimenreplicate always has a key and will never be underconstrained

xml_func.py: process(): Fixed bug where an evaluated XML function might create a node of the same name as an existing node, but these nodes would not be merged even though they referred to the same object, by merging siblings of a newly-evaluated (replaced) node if they have the same name

xml_dom.py: Added merge() and merge_adjacent()

xml_dom.py: replace_with_text(): Return the new node

mappings/VegX-VegBIEN.stems.csv: Indirect voucher mappings: Removed no longer needed ":[*_id/taxonoccurrence]" because a specimenreplicate is a taxonoccurrence, so it doesn't need to have an empty taxonoccurrence

mappings/VegX-VegBIEN.stems.csv: Fixing specimenreplicate->taxonoccurrence mapping bug where taxonoccurrence_id is no longer used as an fkey because it's instead a pkey inherited from taxonoccurrence, by instead using the new fkey to plantobservation for direct vouchers. Note that a duplicate aggregateoccurrence is created, because the _if XML function runs after the XPaths have created the initial tree, and thus the nodes it pulls forward do not automatically get merged with adjacent nodes of the same name. This will eventually need to be fixed by auto-merging the nodes.

schemas/vegbien.sql: specimenreplicate: Fixing specimenreplicate->taxonoccurrence mapping bug where taxonoccurrence_id is no longer used as an fkey because it's instead a pkey inherited from taxonoccurrence, by instead adding an fkey to plantobservation for direct vouchers. Also, it makes more sense for a specimenreplicate to directly voucher the plant it came from rather than that plant's taxonoccurrence, because a direct voucher is a closer relationship to the plant.

mappings/VegX-VegBIEN.stems.csv: Map collectiondate to specimenreplicate via voucher when the voucher is indirect, rather than always directly to the taxonoccurrence, because the collectiondate relates to the specimenreplicate, not the taxonoccurrence, and is not necessarily 1:1 with it

mappings: Updated for_review VegX-VegBIEN mappings, which hadn't been auto-updated because of a modification time issue. (mappings/VegX-VegBIEN.stems.csv was replaced with an older version, which did not trigger make to remake files depending on it.)