TOON: Move PathFindingHeap API to use int16 for x,y coordinates.

The internal x,y point representation was already changed to int16
anyway, so this just harmonises this with the external API (and with
Common::Point which uses int16).
TOON: Minor cleanup and formatting fixes to Pathfinding class.
TOON: Remove unecessary usages of g_system.
TOON: Reduce unecessary linkages in Pathfinding class.
TOON: Further cleanup to Pathfinding Class.

Removal of some unused variables, logical reordering of functions and
minor changes to reduce minor duplication. No functional changes.
TOON: Replace Pathfinding _tempPath static buffers with Common::Array.
TOON: Replace Pathfinding retPath static buffers with Common::Array.
SCI: Initial implementation of AddLine, UpdateLine, DeleteLine
TOON: Minor cleanups in Pathfinding class. No functional change.
SCI: Update information on kGetSierraProfileInt

Thanks to LePhilousophe for his feedback and observations on this
SCUMM: Create proper engine for heversion 101

Regression from 3968f3194893d88d1a8d73eef535b801e5415765
GUI: Get rid of SaveLoadChooser::setSaveMode.

We already pass the title and process button name to the constructor of
SaveLoadChooser and then do not offer any way of changing it, thus changing
the edit mode of the chooser is kind of pointless and was never actually used.
Instead we pass the mode on SaveLoadChooser construction now.
MOHAWK: Do not call close on SaveLoadChooser.

This is actually always called when a dialog closes, thus manual closing is
not required. It furthermore is actually *bad* to call this from outside the
dialog's code, since it will remove the top dialog from the dialog stack and
thus mess up the GUI in case multiple dialogs are opened.
PARALLACTION: Do not call close on a SaveLoadChooser.
GUI: Add helper to SaveLoadChooser, which uses the currently active target.

This reduces the code duplication in all client code, which formerly duplicated
the querying of the plugin, game id etc. and now simply calls the newly added
method runModalWithCurrentTarget() on a SaveLoadChooser object.
GUI: Refactor default savegame description creation.

Formerly the GMM, AGI and SCI duplicated the logic for USE_SAVEGAME_TIMESTAMP.
Now I added a method to SaveLoadChooser instead, which takes care of this. This
might not be the best placement of such a functionality, thus I added a TODO
which talks about moving it to a better place.
TOON: Migrate Pathfinding API x,y coordinates to int16.

This harmonises the usage with Common::Point.
TOON: Migrate Pathfinding Path Buffers to Common::Point.

This removes the need for i32Point, which used int32, instead of the
int16 of Common::Point. Since the co-ordinates passed in are in int16,
this is safe. Tested with no regressions.

Also, removed return value from walkLine function as it always returned
true.
TOON: Minor type fixes and cleanups in Pathfinding class.
GOB: Rewrite the AdLib players

This is a complete rewrite of the AdLib players for ADL and MDY/TBR
files in the Gob engine.

Major changes
1) The AdLib base class is now completely separated from all file
   format code and can theoretically be used by any OPL2-based
   format (within reason)
2) The new code is far better documented and more readable
3) The MDY player now actually works. The MDY/TBR format is
   in reality the MUS/SND format created by AdLib as a simpler
   alternative to the ROL format
4) Since the MAME emulator is quite buggy and leads to noticable
   wrong percussion in the Gobliins 2 title music, the new AdLib
   player will try to create a DOSBox OPL. If it's not compiled in,
   or if the user configured opl_driver to "mame", it will print
   out appropriate warnings.