** Changes in Allout

*** Some previously rough topic-header format edge cases are reconciled.
Level 1 topics use the mode's comment format, and lines starting with the
asterisk - for instance, the comment close of some languages (eg, c's "*/"
or mathematica's "*)") - at the beginning of line are no longer are
interpreted as level 1 topics in those modes.

*** Many or most commonly occuring "accidental" topics are disqualified.
Text in item bodies that looks like a low-depth topic is no longer mistaken
for one unless its first offspring (or that of its next sibling with
offspring) is only one level deeper.

For example, pasting some text with a bunch of leading asterisks into a
topic that's followed by a level 3 or deeper topic will not cause the
pasted text to be mistaken for outline structure.

The same constraint is applied to any level 2 or 3 topics.

This settles an old issue where typed or pasted text needed to be carefully
reviewed, and sometimes doctored, to avoid accidentally disrupting the
outline structure.  Now that should be generally unnecessary, as the most
prone-to-occur accidents are disqualified.

*** Allout now refuses to create "containment discontinuities", where a
topic is shifted deeper than the offspring-depth of its container.  On the
other hand, allout now operates gracefully with existing containment
discontinuities, revealing excessively contained topics rather than either
leaving them hidden or raising an error.

*** Topic cryptography added, enabling easy gpg topic encryption and
decryption.  Per-topic basis enables interspersing encrypted-text and
clear-text within a single file to your heart's content, using symmetric
and/or public key modes.  Time-limited key caching, user-provided
symmetric key hinting and consistency verification, auto-encryption of
pending topics on save, and more, make it easy to use encryption in
powerful ways.  Encryption behavior customization is collected in the
allout-encryption customization group.

*** Navigation within an item is easier.  Repeated beginning-of-line and
end-of-line key commands (usually, ^A and ^E) cycle through the 
beginning/end-of-line and then beginning/end of topic, etc.  See new
customization vars `allout-beginning-of-line-cycles' and
`allout-end-of-line-cycles'.

*** New or revised allout-mode activity hooks enable creation of
cooperative enhancements to allout mode without changes to the mode,
itself.

See `allout-exposure-change-hook', `allout-structure-added-hook',
`allout-structure-deleted-hook', and `allout-structure-shifted-hook'.

`allout-exposure-change-hook' replaces the existing
`allout-view-change-hook', which is being deprecated.  Both are still
invoked, but `allout-view-change-hook' will eventually be ignored.
`allout-exposure-change-hook' is called with explicit arguments detailing
the specifics of each change (as are the other new hooks), making it easier
to use than the old version.

There is a new mode deactivation hook, `allout-mode-deactivate-hook', for
coordinating with deactivation of allout-mode.  Both that and the mode
activation hook, `allout-mode-hook' are now run after the `allout-mode'
variable is changed, rather than before.

*** Default command prefix was changed to "\C-c " (control-c space), to
avoid intruding on user's keybinding space.  Customize the
`allout-command-prefix' variable to your preference.

*** Allout now uses text overlay's `invisible' property for concealed text,
instead of selective-display.  This simplifies the code, in particular
avoiding the need for kludges for isearch dynamic-display, discretionary
handling of edits of concealed text, undo concerns, etc.

*** There are many other fixes and refinements, including:

   - repaired inhibition of inadvertent edits to concealed text, without
     inhibiting undo; we now reveal undo changes within concealed text.
   - auto-fill-mode is now left inactive when allout-mode starts, if it
     already was inactive.  also, `allout-inhibit-auto-fill' custom
     configuration variable makes it easy to disable auto fill in allout
     outlines in general or on a per-buffer basis.
   - allout now tolerates fielded text in outlines without disruption.
   - hot-spot navigation now is modularized with a new function,
     `allout-hotspot-key-handler', enabling easier use and enhancement of
     the functionality in allout addons.
   - repaired retention of topic body hanging indent upon topic depth shifts
   - bulleting variation is simpler and more accommodating, both in the
     default behavior and in ability to vary when creating new topics
   - mode deactivation now does cleans up effectively, more properly
     restoring affected variables and hooks to former state, removing
     overlays, etc.  see `allout-add-resumptions' and
     `allout-do-resumptions', which replace the old `allout-resumptions'.
   - included a few unit-tests for interior functionality.  developers can
     have them automatically run at the end of module load by customizing
     the option `allout-run-unit-tests-on-load'.
   - many, many other, more minor tweaks, fixes, and refinements.
   - version number incremented to 2.2