Redesign the Ban List window.  Closes Issues #303, #342, #427

This is a combination of 18 commits.
 The first commit's message is:
Here is the initial banlist branch of RichardHitt/hexchat.
Changed files are only src/fe-gtk/{banlist.c,fe-gtk.h}.
This version works and contains my first efforts at selective
sensitization of radio buttons and control buttons.

From this point I intend to undertake a stepwise redesign.

Step 1 will be to make the existing banlist code work for
multiple simultaneous banlist windows (for different channels,
obviously).  It will be a hackathon with the only goal of getting
it working.

Step 2 will be the objectization and alpha-stage tidying-up of
all the terrible looking stuff I will have done in Step 1.

 This is the 2nd commit message:

Here's the post-Step-1 commit.  It works for multiple banlist windows.

Note particularly what I've done to banlist.h.
Note that for many functions in banlist.c the argument is now
a banlist_info *, rather than a session *.
Note in banlist.c the initialization of array modes[] which
contains driving information for the checkboxes.

Of course those checkboxes aren't yet implemented.  Maybe in Step 2
I will change to checkboxes from radio buttons; but definitely I will
change to letting modes[] drive processing.

 This is the 3rd commit message:

Converted to checkboxes.  Much additional work.
Note that the infrastructure for Auto-invite is not yet
present in the hexchat tree.  I'm nearly done with banlist,
I think!

 This is the 4th commit message:

Fleshed out 'invite'.  Tagged masks uniformly, e.g. (b) (e) (I).
General cleanup, nearly at the point of beta quality.

 This is the 5th commit message:

Added fourth mode type: quiet.  Did lots and lots of cleanup.  Beta-ready?

 This is the 6th commit message:

Get the banlist timestamps properly sortable.

 This is the 7th commit message:

Redesign the supports_foo() routines.  Now they're responsible for setting
the flags in ->capable, ->readable, ->writeable.

 This is the 8th commit message:

Deleted a couple of RBH comments.

 This is the 9th commit message:

Now the ESC key will close the banlist window.

 This is the 10th commit message:

Fix the fe-text occurrence of fe_add_ban_list().

 This is the 11th commit message:

Fixed also fe_ban_list_end() and removed fe_is_banwindow().

 This is the 12th commit message:

Use old-style initialization for array of structures modes[]

 This is the 13th commit message:

Oops, incomplete regression of modes[] initialization.  This fixes.

 This is the 14th commit message:

Fixed strptime buy implementing a special version here.
Fixed column width concerns by setting resizable and autosize.

 This is the 15th commit message:

Get rid of testing line.

 This is the 16th commit message:

Changed to gtkutil_destroy_on_esc ()

 This is the 17th commit message:

Remove no-longer-used functnion

 This is the 18th commit message:

Minor cleanups to banlist.c, banlist.h

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 Author:    RichardHitt <rbh00@netcom.com>
 Committer: Richard Hitt <rbh00@f17.rbh00.pacbell.net>

 Not currently on any branch.
 Changes to be committed:
   (use "git reset HEAD <file>..." to unstage)

	modified:   src/common/fe.h
	modified:   src/common/hexchat.h
	modified:   src/common/inbound.c
	modified:   src/common/modes.c
	modified:   src/common/proto-irc.c
	modified:   src/common/server.c
	modified:   src/fe-gtk/banlist.c
	modified:   src/fe-gtk/banlist.h
	modified:   src/fe-gtk/fe-gtk.c
	modified:   src/fe-gtk/fe-gtk.h
	modified:   src/fe-gtk/maingui.c
	modified:   src/fe-text/fe-text.c