Tweaked alt-tag encoding to match color/dir naming order

This is mainly to avoid mistakes caused by names/encodings disagreeing:

  LFSR_TAG_ALT  0x4kkk  v1cd kkkk -kkk kkkk
                        ^ ^^ '------+-----'
                        '-||--------|------- valid bit
                          '|--------|------- color
                           '--------|------- dir
                                    '------- key

Notably, the LFSR_TAG_ALT() macro has already caused issues by being
both 1. ambiguous, and 2. not really type-checkable. It's easy to get
the order wrong and things not really break, just behave poorly, it's
really not great!

To be honest the exact order is a bit arbitrary, the color->dir naming
appeared by accident because I guess it felt more natural. Maybe because
of English's weird implicit adjective ordering? Maybe because of how
often conditions show up as the last part of the name in other
instruction sets?

At least one plus is that this moves the dir-bit next to the key. This
makes it so all of the condition information is encoding is the lowest
13-bits of the tag, which may lead to minor optimization tricks for
implementing flips and such.

Code changes:

           code          stack
  before: 34080           2864
  after:  34068 (-0.0%)   2864 (+0.0%)

scripts/dbgtag.py

@@ -40,8 +40,8 @@ TAG_SHRUB           = 0x1000
 TAG_CKSUM           = 0x3000
 TAG_ECKSUM          = 0x3100
 TAG_ALT             = 0x4000
-TAG_GT              = 0x2000
-TAG_R               = 0x1000
+TAG_R               = 0x2000
+TAG_GT              = 0x1000
 
 
 # some ways of block geometry representations