Make init.sage work

[kcrisman]

Ideally, this would later be changed to use attach again.

[kcrisman]

This would fix #251. Needs review.

[kcrisman]

An interesting point is that there is a separate place with an init.sage file expected in DOT_SAGENB:

def load_any_changed_attached_files(self, s):
r"""
Modify ``s`` by prepending any necessary load commands
corresponding to attached files that have changed.
"""
A = self.attached_files()
init_sage = DOT_SAGENB + 'init.sage'
if not init_sage in A.keys() and os.path.exists(init_sage):
A[init_sage] = 0

Maybe people won't want init.sage in the notebook... well, easy enough to just move it, I suppose.

[migeruhito]

I tested your patch, and init.sage is correctly loaded.

Ideally, this would later be changed to use attach again.

I'm not sure. This is the documented behavior, but it is the expected behavior for the average user? In almost all the software we run, a init process means an immutable startup procedure.

An interesting point is that there is a separate place with an init.sage file expected in DOT_SAGENB:

At a first glance, it seems to me an inconsistent coding practice, but I haven't yet a deep and global understanding of the notebook a its code. This code could be there for a reason (an undocumented reason, as far as I know).

[kcrisman]

Thanks!