Create WRF-Chem data handler

Create a Default WRF-Chem data handler. The data handler should be able to

• Read WRF-Chem data
• Extract the column (height and time) for a given lat/lon coordinates
• Creates labels (e.g. conc's on surface cell at time t_i where i > 0
• Creates inputs (e.g. vars from column for times t_{-J} to t_{0}, where J is the total number of previous time steps.