v2.4

SAM@Harvard v2.4

Diff since v2.3

• Adding mock Hadley Cell (half-sine vertical velocity of ascent and descent)
• Adding driven-equilibrium methodology as a substitute to the subsidence() code
• Adding support for writing stat output to seperate files every some steps to avoid large files
• Debug the bulksfcflx formula/code
• Adding the time-dependent and static versions of Kuang [2008]'s linear gravity wave
• Debugging the WTG and SWTG codes, reset wwtg to zero at every timestep