Timer: Move internal scores to new objective and document them

This moves internal scores used by the timer from 91.timer.main to
91.timer.intern.

The sole constant (value 60) was also moved from 91.timer.const to the
new objective, and the const objective was removed.

All internal score holders are also properly documented now (Work
towards #5)

data/neun_einser.timer/functions/internal/init.mcfunction

@@ -93,14 +93,29 @@ scoreboard objectives add 91.timer.main dummy
 #declare score_holder $hours
 
 #>
-# This scoreboard is used to store constant values.
+# Internal scoreboard for non-temporary memory
 #
 # @internal
-scoreboard objectives add 91.timer.const dummy
+scoreboard objectives add 91.timer.intern dummy
 
 #>
 # @internal
 #declare score_holder 60
-scoreboard players set 60 91.timer.const 60
+scoreboard players set 60 91.timer.intern 60
+
+#>
+# Raw time the world border was started at. The world border is reset once it
+# reaches a certain threshold to prevent it running out of blocks.
+# @internal
+#declare score_holder $start
+#>
+# Blocks the world border travels per second. Used for some internal
+# calculations.
+#
+# For example, if this was started with neun_einser.timer:start/millis, this
+# will be 1000.
+#
+# @internal
+#declare score_holder $blocks_per_second
 
 data merge storage neun_einser.timer:display {"hh:mm:ss.s": '[{"storage": "neun_einser.timer:display", "nbt": "internal.hours", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.minutes", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.seconds", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.millis", "interpret": true}]', "hh:mm:ss": '[{"storage": "neun_einser.timer:display", "nbt": "internal.hours", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.minutes", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.seconds", "interpret": true}]', "hh:mm": '[{"storage": "neun_einser.timer:display", "nbt": "internal.hours", "interpret": true}, {"storage": "neun_einser.timer:display", "nbt": "internal.minutes", "interpret": true}]'}

data/neun_einser.timer/functions/read.mcfunction

@@ -4,10 +4,10 @@ scoreboard players operation $millis 91.timer.main = $raw 91.timer.main
 scoreboard players operation $seconds 91.timer.main = $millis 91.timer.main
 scoreboard players operation $seconds 91.timer.main /= $blocks_per_second 91.timer.main
 scoreboard players operation $minutes 91.timer.main = $seconds 91.timer.main
-scoreboard players operation $minutes 91.timer.main /= 60 91.timer.const
+scoreboard players operation $minutes 91.timer.main /= 60 91.timer.intern
 scoreboard players operation $hours 91.timer.main = $minutes 91.timer.main
-scoreboard players operation $hours 91.timer.main /= 60 91.timer.const
+scoreboard players operation $hours 91.timer.main /= 60 91.timer.intern
 
 scoreboard players operation $millis 91.timer.main %= $blocks_per_second 91.timer.main
-scoreboard players operation $seconds 91.timer.main %= 60 91.timer.const
-scoreboard players operation $minutes 91.timer.main %= 60 91.timer.const
+scoreboard players operation $seconds 91.timer.main %= 60 91.timer.intern
+scoreboard players operation $minutes 91.timer.main %= 60 91.timer.intern