List of initial drilling state switches and equations to be available in Tempus

Child of #588

Based on a quick review of several basic drilling monitoring log formats and viewers, here is the initial list of drilling status flags and equations I think we should start with.

** Need to details out each calculation with it's attendant preliminary calcs.

Drilling state and flags:

1. Drilling state engine
2. Bit on bottom, =1 when hole depth - bit depth < 1 ft, =0 otherwise.
3. Block direction, ="up" when block_position(n) - block_position(n-1) >0, = "down" when block_position(n) - block_position(n-1)<0, ="stopped" otherwise.

Drilling base calculations:
1. Stick Slip RPM peak to peak = max of RPM - min of RPM over time window X
2. Stick Slip Torque peak to peak = max of Torque - min of Torque over time window X
3. Block Velocity = [block_position(n) - block_position(n-x)] / [timestamp(n) - timestamp(n-x)]
4. Mud Pressure at depth
5. ECD