more idiomatic variable names

Dependencies

• [2] P5QNVXSN drop final mention of state global beyond main.lua
• [3] LF7BWEG4 group all editor globals
• [4] UHB4GARJ left/right margin -> left/right coordinates
• [5] 7SFHSB47 rename
• [6] RT6EV6OP delegate update events to drawings
• [7] JFFUF5AL override mouse state lookups in tests
• [8] KTZQ57HV replace globals with args in a few functions
• [9] PJEQCTBL add state arg to Drawing.update
• [10] DRFE3B3Z mouse buttons are integers, not strings
• [11] LAW2O3NW extract variable Margin_left
• [*] BLWAYPKV extract a module

Change contents

• replacement in drawing.lua at line 244
  [3.254]→[3.2289:2333](∅→∅)
  − local x, y = App.mouse_x(), App.mouse_y()
  [3.254]

  [3.1585]
  + local pmx, pmy = App.mouse_x(), App.mouse_y()
• replacement in drawing.lua at line 246
  [3.1613]→[3.5958:6027](∅→∅)
  − if Drawing.in_drawing(drawing, x,y, State.left,State.right) then
  [3.1613]

  [3.384]
  + if Drawing.in_drawing(drawing, pmx,pmy, State.left,State.right) then
• replacement in drawing.lua at line 250
  [3.614]→[2.1465:1569](∅→∅)
  − local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-drawing.y, State.width)
  [3.614]

  [3.684]
  + local mx,my = Drawing.coord(pmx-State.left, State.width), Drawing.coord(pmy-drawing.y, State.width)
• replacement in drawing.lua at line 257
  [3.457]→[3.6028:6098](∅→∅),[3.6098]→[2.1570:1672](∅→∅)
  − if Drawing.in_drawing(drawing, x, y, State.left,State.right) then

  − local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-drawing.y, State.width)
  [3.457]

  [3.949]
  + if Drawing.in_drawing(drawing, pmx, pmy, State.left,State.right) then

  + local mx,my = Drawing.coord(pmx-State.left, State.width), Drawing.coord(pmy-drawing.y, State.width)