Eg. if you --pivot code, postings from transactions with no code value
were formerly displayed with the unpivoted account name, so you'd see
a mixture of account names and codes. Now we always pivot the account name,
to blank if nothing else. This probably makes reports pretty ugly, it's just another
step towards making --pivot's behaviour clearer.
* Add implicit tags code/desc/payee for --pivot
Additionally allow using of transaction inherited tags.
* Use original posting in query by account name
To be able to query on individual postings and by account name it is
useful to have access to original account name (before pivot).
Especially this is useful when all postings within transaction gets
the same pivot name due.
As a side effect we'll match by alias.
Note: to query on amt it usually expected to see matches with inferred
amounts.
