[WIP] Add Work doctype for recording crop cycle operations

[Tropicalrambler]

https://github.com/ERPNext-Agri-Community/erpnext-agri/issues/3

As I was working on the Fertilizer Application or Pesticide Application, it dawned on me that we can simplify greatly by having a SINGLE DocType which handles all the functionality for these types of work:

Planting Transplanting / moving animals Doing field work on the plants/ field / animals Applying Fertilizer / feeding Applying Pesticides / medication Harvesting Post-harvest work Work Done Each of the above should belong to a Work Done DocType, and upon opening, the farmer selects: a. Crop Cycle or Life Cycle (or herd) b. Specific Crop Cycle or Life Cycle c. Work Type (as above) d. Date

The selections made in these four fields, enable or disable those child tables relevant to the type of work being done. A harvest does not involve the application of pesticides.