respect order_start/order_end in extraction

[leejjoon]

I think this is something that I started at some point but never finished. It lets you specify start/end order number to extract spectra. This was meant to solve issues like #29.

With this change, one can set the optional order-range parameter in the command line like below

python igr_pipe.py stellar-ab 20240429 -b H -g 190 --order-range="105,115"

Or, add the following lines to the "recipe.conf" so that that option is applied by default, for example,

"""
[EXTRACTION]
ORDER_START_H=100
ORDER_END_H=122
ORDER_START_K=73
ORDER_END_K=93
"""

For now, it simply drops the "WAT" header. I think this is rarely used (the exception is IRAF I guess?) so should be okay.