Update initializing.rst
Merge pull request #40 from mhvk/placeholder

Small corrections to allow longslit day arcs
added a better description for initializing
Merge pull request #41 from wkerzendorf/docs/update

added a better description for initializing
interlinked the prepare functions with the GMOSMOSRAWFITS object.
added documentation for the "new" prepare structure.
fixed some typos in the documentation
Ensure writing linetables to hdf5 works again, by circumventing self.filled()
Merge pull request #45 from mhvk/wavecal-table-interaction

Ensure writing linetables to hdf5 works again, by circumventing self.filled()
Merge pull request #42 from wkerzendorf/gmos/easy_prepare

Some changes to make preparing easier (and unlink a little from DB)
added various longslit related tasks
added mhvk's copper argon line list
added some of MHVK's documentation
added the longslit arcs setup.
fixed wrong keyword
linking longslit arcs procedure finished
in the process of implementing longslit calibration
updated representation for longslit
in the process of saving the wavelength calibration to the database
finished the wavecal. updated the documentation