Compute bar layout options instead of tabulating pfGridmath

pfGridmath listed every exact cols x rows grid per bar size; the only
live use was seeding the layout dropdown, which a divisor loop now does.

Everything else that read it was unreachable: every layout option is a
"cols x rows" string, so ResolveBarLayout's BarLayoutFormfactor lookup
never matched, and the actionbar module resets a stored layout that
isn't one before BarLayoutSize/BarButtonAnchor run, so their fallbacks
never fired. BarLayoutFormfactor and env/tables.lua go with it.

env/tables.lua

@@ -1,15 +0,0 @@
--- barlength = {[formfactor]={cols, rows}}
-pfGridmath = {
-  [1] = {{1,1}},
-  [2] = {{2,1},{1,2}},
-  [3] = {{3,1},{1,3}},
-  [4] = {{4,1},{2,2},{1,4}},
-  [5] = {{5,1},{1,5}},
-  [6] = {{6,1},{3,2},{2,3},{1,6}},
-  [7] = {{7,1},{1,7}},
-  [8] = {{8,1},{4,2},{2,4},{1,8}},
-  [9] = {{9,1},{3,3},{1,9}},
-  [10] = {{10,1},{5,2},{2,5},{1,10}},
-  [11] = {{11,1},{1,11}},
-  [12] = {{12,1},{6,2},{4,3},{3,4},{2,6},{1,12}}
-}