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/druid.lua

@@ -12,6 +12,9 @@ M.comps = {
 	android_back = require("druid.base.android_back"),
 	text = require("druid.base.text"),
 	timer = require("druid.base.timer"),
+	progress = require("druid.base.progress"),
+
+	progress_rich = require("druid.rich.progress_rich"),
 }