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/__readable.lua

@@ -29,7 +29,7 @@ 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

share/scripts/_find_nonzero_sample.lua

@@ -42,10 +42,10 @@ 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]) > 0 then
 						if (nonzeropos < 0 or pos + i < nonzeropos) then
-							nonzeropos = pos + i
+							nonzeropos = pos + i - 1
 						end
 						break
 					end

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