Add place holder columns into SynGen

[jinningwang]

Hantao,

Can we have some placeholder columns in the SynGen group? These columns are included in Manpower generator data file: ramp_agc, ramp_10, ramp_30, ramp_q, apf. They are explained as:

RAMP AGC: ramp rate for load following/AGC (MW/min)
RAMP 10: ramp rate for 10 minute reserves (MW)
RAMP 30: ramp rate for 30 minute reserves (MW)
RAMP Q: 20 ramp rate for reactive power (2 sec timescale) (MVAr/min)
APF: area participation factor

They can be useful for interoperability modules. I can do this, what do you think?

Regards,
Jinning