Store hybrid parameters (ptop,rcoef,pref) in the axis object.

Use these parameters directly instead of trying to solve for them from A,B.
Encode the time axis information for FSTD files.

Also, use 64-bit integers internally when converting from dates to stamps.
Detect Forecast axes, in addition to vertical axes, when setting up to write an FSTD file.

Include 'deet' information in the Forecast axis, so it can be re-encoded back
into FSTD files.
Encode HY record information from Hybrid axes.
Encode the Forecast axis as NPASAxis, before writing to an FSTD file.

Multiple stages of the FSTD file creating will need this information.
Fix bug when there are no vertical records to write.

encode_vertical should always return an ndarray, even if it's empty.
Extract additional information from !! records.

This information will be required for re-writing the data back to FSTD files.
Propogate metadata for Hybrid and LogHybrid axes.

We need this information for writing out FSTD files.
Modify fstd_core.get_loghybrid_table to take an encoded table (ndarray) and return a dictionary of axis attributes.

This will make it easier to stick the attributes into the axis, without having
to pick them apart and put them back together.
Change fstd_core.get_loghybrid_a_b to take a dictionary as input.

The individual parameters (ip1_m, a_m, etc.) can be extracted within the method.
Rename fstd_core.get_loghybrid_table to fstd_core.decode_loghybrid_table.