scons: Pass -Qunused-arguments to clang to skip warnings about unused -I paths

Step 1/2 in making it possible to build in strict mode with clang 3.3
and scons here.
scons: Pass -Wno-parentheses-equality to clang for src/lua/ library objects

Step 2/2 in making it possible to build in strict mode with clang 3.3
and scons here.
New macros AI_SAVE_GOLD and AI_SAVE_GOLD_DEFAULT

… to make enabling gold saving for the AI simpler in a scenario now
that it is not the default any more.
SotBE S1: use new macro AI_SAVE_GOLD_DEFAULT
Adds -Wextra-semi to pedantic compilation.

Also fixes all warning messages.
resources: Delete tree, it's now split to a different repository
UtBS 12: Remove keys where values match default
UtBS 12: Remove num_keys_found variable
UtBS 12: unstore_unit is capable of relocating units
UtBS 12: Spawn bats on rainforest, not tropical forest

While there was some tropical forest on the map, most has been changed
to rainforest. This change ensures that the bats stay in the jungle
proper. Also, by eliminating tropical forest as an option, the bats
will never spawn in the trees in the southern part of the island.
UtBS 12: Get rid of overridden flag variant
[wmlunits] for campaigns, define a difficulty

The first preprocessor symbol listed in a campaigns difficulties=...
attribute is now set when parsing WML looking for unit definitions.
SotBE S11: add waves of mermen, number dependent on difficulty
SotBE S11: ensure correct number of gryphon riders is recruited

The previous method set the maximum limit correctly and worked well
before 1.11.7.  However, the new recruitment algorithm hardly recruits
gryphon riders at all in this scenario without extra instructions.  The
new AI instructions ensure that it does.
[wmlunits] add some debug info
UtBS 3: Remove orc_warning variable
UtBS 3: Activate shroud turn 12 instead of turn 1

No longer need to clear shroud at game start
UtBS 3: No need to store Garak's location separately
UtBS 3: Don't include early finish bonus in objectives when there is no turn limit
UtBS: Remove unused image

Was campaign image, reference removed in
987b1d96502c16953c64c91826137b80065f1759