[datetime_picker] convert to pure library, improve Readme with control details and sample code

apps/alarm/app.js

@@ -123,7 +123,6 @@ function showNewMenu(group) {
 }
 
 function showEditAlarmMenu(selectedAlarm, alarmIndex, withDate, scroll, group) {
-  console.log(scroll);
   var isNew = alarmIndex === undefined;
 
   var alarm = require("sched").newDefaultAlarm();

apps/datetime_picker/README.md

@@ -1,9 +1,36 @@
 # App Name
 
-Datetime Picker allows to swipe along the bars to select date and time elements, e.g. for the datetime of Events in the Alarm App.  As a standalone app, it allows to see the weekday of a given date and, once a datetime is selected, the number of days and time between that datetime and now.
+Datetime Picker allows to swipe along the bars to select date and time elements, e.g. for the datetime of Events in the Alarm App.
 
 Screenshot: ![datetime with swipe controls](screenshot.png)
 
 ## Controls
 
 Swipe to increase or decrease date and time elements.  Press button or go back to select shown datetime.
+
+![datetime with numbered swipe controls](screenshot2.png)
+
+1. Year: swipe up to increase, down to decrease
+2. Month: swipe right to increase, left to decrease
+3. Day: swipe up to increase, down to decrease
+4. Week: swipe up to increase week (same day next week), down to decrease (same day previous week)
+5. Weekday: swipe right to increase, left to decrease (basically the same effect as 3, but with a focus on the weekday)
+6. Hour: swipe right to increase, left to decrease
+7. Minutes: swipe right to increase, left to decrease
+8. 15 minutes: 00, 15, 30 or 45 minutes; swipe up to increase, down to decrease; wrap-around i.e. goes back to 00 after increasing from 45
+
+## How to use it in code
+
+Sample code which would show a prompt with the number of days and hours between now and the selected datetime:
+
+    require("datetimeinput").input().then(result => {
+        E.showPrompt(`${result}\n\n${require("time_utils").formatDuration(Math.abs(result-Date.now()))}`, {buttons:{"Ok":true}}).then(function() {
+            load();
+        });
+    });
+
+To set the initial value, pass a Date object named _datetime_, e.g. for today at 9:30 :
+
+        var datetime = new Date();
+        datetime.setHours(9, 30);
+        require("datetimeinput").input({datetime}).then(...

apps/datetime_picker/metadata.json

@@ -2,15 +2,16 @@
   "name": "Datetime picker",
   "shortName":"Datetime picker",
   "version":"0.01",
-  "description": "Allows to pick a date and time by swiping.",
+  "description": "A library that allows to pick a date and time by swiping.",
   "icon":"app.png",
+  "type":"datetimeinput",
   "tags":"datetimeinput",
   "supports" : ["BANGLEJS2"],
+  "provides_modules" : ["datetimeinput"],
   "readme": "README.md",
   "screenshots" : [ { "url":"screenshot.png" } ],
   "storage": [
     {"name":"datetimeinput","url":"lib.js"},
-    {"name":"datetime_picker.app.js","url":"app.js"},
     {"name":"datetime_picker.img","url":"app-icon.js","evaluate":true}
   ]
 }