[ccomb]

Read and edit a database's own parameters, and restate what reads them

A database's own parameters, the ones every process reads unless it
defines its own of the same name, can now be read with
GET /db/{db}/parameters and set or removed with
POST /db/{db}/parameters (setParameters, removeParameters).

Every process that reads an edited parameter, directly or through a
calculated one, is restated as an edit of that process would restate it,
and the answer lists the processes that moved. Example: the database has
salt_kg = 0.01 and salt_g = salt_kg * 1000, and a flour process has a
line salt_g / 100 (0.1 kg). Setting salt_kg to 0.02 moves that line
to 0.2 kg, and salt_g shows 20.

Refused, with the reason: the checks of an activity's parameters (a name
that is not one word of the language, a second spelling, a value that is
not finite, a formula that does not read or loops); removing a parameter
that a formula still reads, naming the readers; an edit that leaves a
process without a value, or a calculated parameter read by no process
newly without one; a change that moves an allocation share.

Journal op parameters. REST, the assistant's get_database_parameters
and edit_database_parameters, pyvolca database_parameters() and
edit_database_parameters(). Reading them needs the licence to read the
inventory. Wire revision 74.