implement settings version #120 and migration #134

Latest changes for history support move configuration files into
history directory to keep them as timestamp for last read. This code
also adds reading of old configuration files (but does not remove them)

settings.lua

@@ -29,10 +29,35 @@ function HistoryToPath(history)
 end
 
 function DocSettings:open(docfile)
+	-- history feature moves configuration files into history directory
 	lfs.mkdir("./history")
 	local new = { file = DocToHistory(docfile), data = {} }
 	local ok, stored = pcall(dofile,new.file)
+	if not ok then
+		ok, stored = pcall(dofile,docfile..".kpdfview.lua")
+	end
 	if ok then
+		if stored.version == nil then
+			stored.version = 0
+		end
+
+		if stored.version < 2012.05 then
+			debug("settings", docfile, stored)
+			if stored.jumpstack ~= nil then
+				stored.jump_history = stored.jumpstack
+				stored.jumpstack = nil
+				if not stored.jump_history.cur then
+					stored.jump_history.cur = 1
+				end
+			end
+			if stored.globalzoommode ~= nil then
+				stored.globalzoom_mode = stored.globalzoommode
+				stored.globalzoommode = nil
+			end
+			stored.version = 2012.05
+			debug("upgraded", stored)
+		end
+
 		new.data = stored
 	end
 	return setmetatable(new, { __index = DocSettings})