graphics: Add endgame screen graphics.

Freedoom Phase 1 needs endgame screens for the ends of episodes
2, 3 and 4. Add some basic screens that are essentially just
screenshots from level 8 of each episode. Set END0-END6 to be the
dummy empty graphic so that the game doesn't crash after E3.

This (for the time being) fixes the most egregious problems in #32.
graphics: Add animation for E3 end screen.

Use the END0-END6 graphics to make the marine on the PFUB2 animate,
firing a few shots towards the boss corpse.
levels: updated e1m6

Add monsters throughout the map, keyed door flags and the keys
themselves, and all-around fleshes it out. Resolves #33

Signed-off-by: Mike Swanson <mikeonthecomputer@gmail.com>
levels: new e2m1

Replaces the old map that copied the themes from the original Doom
E2M1, this is an original concept instead.

Signed-off-by: Mike Swanson <mikeonthecomputer@gmail.com>
textures: Rewrite Freedoom's texture build system.

Stop using deutex's built-in texture builder and generate our own
texture lumps. This is essential for compatibility reasons: the
entries in the texture/pnames lumps must match the order of those
in the original IWADs. Failure to match ordering means that some
well-known WADs (eg. DTWID) would not work with Freedoom.

This fixes #1, and also means that Freedoom can now be built in
parallel using make's '-j' option.
Merge branch 'master' of github.com:freedoom/freedoom
build: Fix 'make -j' handling.

Some build targets create multiple outputs, which can cause problems
when doing parallel builds. Clean up the build system so that all
subdir invocations come from the top-level Makefile and use $(MAKE).
Also fix the FREEDOOM/FREEDM lumps to really include the version
number by using $(shell ...) syntax.
build: Fix 'make clean'.

lumps/Makefile has been removed, but we were still trying to
make clean in that directory.
levels: Add DM20 level.

This is an old deathmatch level I made years ago.
levels: Update DM19.

Fixes #31, and tweaks items and player starts.
textures: Only include patches needed by textures.

Now that #1 is fixed, we can be certain that all patches needed for
compatibility are definitely being included in the PNAMES lists. It
therefore isn't necessary to include every patch in the patches/
directory in every WAD.

Extend the build-textures script to generate a text file containing
the list of PNAMES, and include this from the main config file. That
way, each IWAD only gets the patches it explicitly needs.
doc: Update BUILD-SYSTEM

Many of the details in this file are now obsolete. Update the
documentation to explain how things are now built (now that we have
a custom texture builder) and include details of some of the other
build scripts in subdirectories.
build: Include sprites in freedoom1.wad for compatibility.

The following unused sprites appeared in doom.wad: APBX, APLS, BOSF,
MANF. These are Doom 2 sprites. Although unused, they can be (and are)
used in mods. Include these in freedoom1.wad for compatibility.
This fixes #36.
build: Fix Makefile dependencies for pnames.txt.

The wadinfo.txt files #include the pnames.txt file generated by the
texture builder: because of this, we must build subdirectories
before building the wadinfo.txt files.
build: Don't include dummy patches for sprites.

Some of the textures in the textures configuration file use sprites
as patches. Because of this, the build system was inserting extra
dummy entries for these "missing" patches. Handle this corner case
and do not insert dummies for sprites. Fixes #40.
Remove Python byte-code in the clean rule.
Merge remote-tracking branch 'fabian/clean_pyc'

Conflicts:
	graphics/text/Makefile