issue17:fix led model memory bug; issue19:header time is not utc bug; issue18:header data-obs\darktime\exposure time fix by shaoli's chart;add new star catalog:C6_50sqdeg_ns.py

fix bug: obs config file defined in pointing list, but not read this file, pointing obs_param is None

Merge branch 'sim_scheduler' of https://csst-tb.bao.ac.cn/code/csst_sim/csst-simulation into sim_scheduler

* Changed the name of output folder of pointing to corresponding pointing.obs_id.
* fixed the order .cat hdr updating and the creation of .cat file.
* Changed the naming of shutter and flat reference image: chip IDs now all in 2 digits.
* Updated the __init__ method of ChipOutput
* Removed Config.py from ObservationSim.Config
* Cleaned codes in ObservationSim.py, ChipOutput

Merge branch 'sim_scheduler' of https://csst-tb.bao.ac.cn/code/csst_sim/csst-simulation into sim_scheduler

Conflicts:
	config/obs_config_SCI_WIDE_phot.yaml

remove pointing_dir, data_dir in overall_config

Merge branch 'sim_scheduler' of https://csst-tb.bao.ac.cn/code/csst_sim/csst-simulation into sim_scheduler

Conflicts:
	ObservationSim/Config/Pointing.py
	config/obs_config_SCI_WIDE_phot.yaml