Cleanup: Removed redundant fatal errors
Fixed|libdeng2|RuleRectangle: Vertical input/output dependencies

The Height output rule was not properly dependent on the vertical
inputs.
Debug|FS1: Moved cache hit/miss messages to TRACE level

Even at DEBUG level these are mostly noise to the user.

Note that in the future caching is mostly handled by de::Bank.
Fixed|Heretic|Hexen: Default look up/down key bindings were inversed

Now matches the vanilla behavior.
Fixed|Heretic: Play ARTIUP when picking up artifacts

Previously both ITEMUP and ARTIUP were played.
Fixed|Heretic: Ambient sound stuttering in multiplayer

Both client and server attempted to play the ambient sounds which
resulted in stuttering on client-side when the start sound deltas
arrived from the server.
Fixed previous commit

IS_NETGAME must be tested also because singleplayer is currently a
special case.
Fixed|Deh Reader: Always update sprite name and action LUTs before parsing patches

Hacx now works as expected when loaded from the Ring Zero GUI.
DED: Parse tokens and strings to de::String buffers

Should also result in a small but noticeable performance improvement
during startup/reset as buffers now grow upward rather than being
trimmed down.
libdeng2: Added Path slash normalization methods

Added methods for replacing slashes with a specific separator character.

This is now used by NativePath instead of QDir's equivalent.
Client|Audio: Lowered level of sound sample cache log message
Snowberry: Use -loglevel instead of the incremental -v option

Added the Trace level as a choice for verbose messages.
Client: Show message box if launch fails

If engine launch fails due to any exception, show a nice message
box with the error message before quitting.
Fixed|Resources: Normalize slashes to forward slashes in URIs

Fixes a problem related to model definitions where the backslashes
used in the URIs would not be found because forward slashes were
expected.
Snowberry: Disable texture compression by default

Texture compression causes visible quality loss in textures and also
may cause stuttering during gameplay as textures are compressed on
the fly. Nowadays graphics cards have plenty of memory, so the default
should be 'no compression'.
Fixed|Hexen: Crash when Dark Servant deals damage

Fixed a problem with damage caused by Dark Servants: if the player
summons the Servant as a pig and then returns to human form, there was
a crash when the Servant attacked somebody because the Servant's
original master (the pig) was already gone.
Fixed|Heretic: Powered-up Wand Crystal missiles

The behavior of the powered-up Wand Crystal missiles did not conform
to vanilla Heretic behavior, likely due to refactoring oversight
somewhere along the way.

Reinstated the vanilla version of Heretic's P_SpawnMissileAngle()
for use with the powered-up wand missiles.
Heretic: Added a comment about vanilla code

Here be vanilla code, beware.
Fixed|Heretic: Hell Staff rain was coming down at an angle

The correct behavior is for the rain to fall down straight.
Fixed|Hexen: Crash when morphing a Dark Servant

There was a potential NULL pointer access if a Minotaur was morphed.