Data Type: Add boolean and time, remove long and double

[jpmckinney]

time is relevant, as some data sources split date and time as different elements.

Also, I'm not sure why we have long and double, since they are just different length integer and real numbers. (Databases have many more numeric types that aren't listed: smallint, bigint, serial, etc.)

Decimal (also "numeric") is also a distinct type. It's more precise than float (which can have floating-point errors). Not sure if we care about retaining that distinction.

Note that different contexts use different words. Not sure which context makes the most sense. Current choice in bold.

• character (ANSI SQL); char, varchar, text (non-standard SQL); string (JSON)
• enum (non-standard SQL); codelist (OCDS)
• float, real (ANSI SQL); number (JSON)
• timestamp (ANSI SQL); datetime (non-standard SQL); date-time (JSON Schema)

These don't have such issues:

• boolean
• date
• time
• integer