Fix BALMLayout archiving issues.

SharedSolver was archiving too many constraints, partly because of
multiple typos, also because it archived some which were just artifacts
of the layout process. These extra constraints are created when the
layout calls SetRange() on the left/top/right/bottom tabs during layout.

* LinearSpec/ActiveSetSolver had to be adjusted to get access to the
constraints added by the SetRange() calls.
* BALM::TabBase was adjusted to avoid a segfault during unarchiving,
caused by an unitialized member.
* ALMFriendLayoutTest was adjusted to include a more obvious custom
constraint for testing.

Add initial support for archiving a BALMLayout.

What's supported:
* basic archive/instantiate
* friend layouts
coming soon:
* saving of custom restraints
* archiving of BadLayoutPolicy

Fix possible NULL dereference in TabBase::IsInLayout().

Refactor XTab and YTab to share a common base, TabBase.

TabBase takes care of layout tracking etc..

Let BALM::{X|Y}Tabs be in multiple BALMLayouts, if they are friendly.

Fix spacing before first header in src/libs/alm.

Also add copyright header in ALMGroup.cpp.

Style cleanup in alm: mostly clean includes.

Make tabs BReferenceable. Maintain a list of tabs.

Fix BALMLayout archiving issues.

SharedSolver was archiving too many constraints, partly because of
multiple typos, also because it archived some which were just artifacts
of the layout process. These extra constraints are created when the
layout calls SetRange() on the left/top/right/bottom tabs during layout.

* LinearSpec/ActiveSetSolver had to be adjusted to get access to the
constraints added by the SetRange() calls.
* BALM::TabBase was adjusted to avoid a segfault during unarchiving,
caused by an unitialized member.
* ALMFriendLayoutTest was adjusted to include a more obvious custom
constraint for testing.

Add initial support for archiving a BALMLayout.

What's supported:
* basic archive/instantiate
* friend layouts
coming soon:
* saving of custom restraints
* archiving of BadLayoutPolicy

Fix possible NULL dereference in TabBase::IsInLayout().

Refactor XTab and YTab to share a common base, TabBase.

TabBase takes care of layout tracking etc..

Let BALM::{X|Y}Tabs be in multiple BALMLayouts, if they are friendly.

Fix spacing before first header in src/libs/alm.

Also add copyright header in ALMGroup.cpp.

Style cleanup in alm: mostly clean includes.

Make tabs BReferenceable. Maintain a list of tabs.