feature: dealing with time zones in the time axis

[jmp75]

Is your feature request related to a problem? Please describe.

The time zone information (or lack thereof if this is ever allowed - prob should not be) can be held in each time stamp in memory, which has its theoretical advantages. BUT mixing this with naive date times potentially created by users may cause more trouble than good thing.

Describe the solution you'd like

See design rationale notebook for discussions