Feature/progress (#17)

* improve example gui. Add simple pages

* return old progress bar with example

* base progress with steps, there is bug with step? 1 ~= 1, small delta?

* polish progress, check float error case

* add callback on end of "to" function, value check

* start of green/red in progress

* add first version of rich progress bar

* make green bar darker

* rich bar fixes

* add delay, before filling in rich progress

* PR fixes

* remove dublicate of 'progress_rich'

druid/rich/progress_rich.lua

@@ -0,0 +1,55 @@
+local settings = require("druid.settings")
+local pr_settings = settings.progress_rich
+
+local M = {}
+
+function M.init(instance, name, red, green, key)
+	instance.red = instance.parent:new_progress(red, key)
+	instance.green = instance.parent:new_progress(green, key)
+	instance.fill = instance.parent:new_progress(name, key)
+end
+
+
+function M.set_to(instance, value)
+	instance.red:set_to(value)
+	instance.green:set_to(value)
+	instance.fill:set_to(value)
+end
+
+
+function M.empty(instance)
+	instance.red:empty()
+	instance.green:empty()
+	instance.fill:empty()
+end
+
+
+function M.to(instance, to, callback)
+	if instance.timer then
+		timer.cancel(instance.timer)
+		instance.timer = nil
+	end
+
+	if instance.fill.last_value < to then
+		instance.red:to(instance.fill.last_value)
+		instance.green:to(to, function()
+			instance.timer = timer.delay(pr_settings.DELAY, false, function()
+				instance.red:to(to)
+				instance.fill:to(to, callback)
+			end)
+		end)
+	end
+
+	if instance.fill.last_value > to then
+		instance.green:to(instance.red.last_value)
+		instance.fill:to(to, function()
+			instance.timer = timer.delay(pr_settings.DELAY, false, function()
+				instance.green:to(to)
+				instance.red:to(to, callback)
+			end)
+		end)
+	end
+end
+
+
+return M