Fix off by one in Lua scripts

Lua arrays (tables) start counting at one.
Also `for i = a, b do .. end` is inclusive: a <= i <= b

share/scripts/s_region_gain.lua

@@ -41,7 +41,7 @@ function factory () return function ()
 				-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
 				local d = cmem:to_float (0):array()
 				-- iterate over the audio sample data
-				for i = 0, s do
+				for i = 1, s do
 					if math.abs (d[i]) > peak then
 						peak = math.abs (d[i])
 					end