Fix Utils.minutesBetween()

minutesBetween(
    new Date(2019, 01, 01, 13, 20, 00), new Date(2019, 01, 01, 14, 20, 00)
)
returned 0 instead of 60, the fixed function property return numbers of
minutes after 60.

TODO.md

@@ -8,10 +8,9 @@
     - Is auto-sizing actually needed, or can we just set a default manual size?
     - Reducable room sidepane, swipe to show full-window
 
-  - When qml syntax highlighting supports ES6 string interpolation, use them
+  - When qml syntax highlighting supports ES6 string interpolation, use that
 
 - Fixes
-  - `minutesBetween()` for 13:13:58 and 14:15:07
   - Pressing backspace in composer sometimes doesn't work
   - Message order isn't preserved when sending a first message in a E2E
     room, then while keys are being shared sending one with another account,

src/qml/utils.js

@@ -125,7 +125,7 @@ function thumbnailParametersFor(width, height) {
 
 
 function minutesBetween(date1, date2) {
-    return Math.round((((date2 - date1) % 86400000) % 3600000) / 60000)
+    return ((date2 - date1) / 1000) / 60
 }