Name the macro slot count

Three loops walked 1..36 by hand, two of them re-arguing in comments why 36
is the right number. It is: the client addresses 18 account-wide macros at
1-18 and 18 character-specific ones at 19-36, and that range is what
GetMacroInfo and C_Macro.SetMacroDisplay index. Nothing in the API hands it
back -- GetNumMacros() returns how many of each tab are used, which cannot be
summed into a range, because the character block still starts at 19 when the
account block is empty. Blizzard's MAX_MACROS is no better: it lives in the
load-on-demand Blizzard_MacroUI and is nil until the macro window is opened.

So CleveRoids.MAX_MACRO_SLOTS in Init.lua, carrying that reasoning once.
ValidateAllMacros also dropped a numAccountMacros it computed and never read.

ReleaseDisplays keeps sweeping the full range rather than the macros it knows
it published: PublishAllDisplays clears that record on each re-parse, so a
macro claimed before one and gone after it would keep our last published value
forever. Releasing a slot we never claimed costs nothing, and it runs once.

Init.lua

@@ -19,6 +19,15 @@ CleveRoids.mouseOverResolvers  = {}
 CleveRoids.mouseoverUnit = CleveRoids.mouseoverUnit or nil
 CleveRoids.mouseOverUnit = nil
 
+-- Every macro slot the client can hold: 18 account-wide (1-18) followed by 18
+-- character-specific (19-36). This is the index space GetMacroInfo and
+-- C_Macro.SetMacroDisplay address, and it is fixed -- GetNumMacros() returns how
+-- many of each tab are *used*, which cannot be summed into a range, because the
+-- character block starts at 19 no matter how few account macros exist. Blizzard's
+-- own MAX_MACROS is no help either: it lives in the load-on-demand Blizzard_MacroUI
+-- and is nil until the player opens the macro window.
+CleveRoids.MAX_MACRO_SLOTS = 36
+
 -- Environment flags
 CleveRoids.hasSuperwow = SetAutoloot and true or false
 CleveRoids.hasTurtle   = (type(_G.TURTLE_WOW_VERSION) ~= "nil")