qt: use series of pngs for spinner

Use a series of .png frames for the spinner instead of a .mng.
`mng` is an obscure image format and is not built by default into Qt5.

This appears to improve the crispness of the spinner as well.

Does not noticably increase the size (still ~27k) and the code
is not more complicated either.

share/qt/make_spinner.py

@@ -1,16 +1,15 @@
 #!/usr/bin/env python
 # W.J. van der Laan, 2011
-# Make spinning .mng animation from a .png
+# Make spinning animation from a .png
 # Requires imagemagick 6.7+
 from __future__ import division
 from os import path
 from PIL import Image
 from subprocess import Popen
 
-SRC='img/reload_scaled.png'
-DST='../../src/qt/res/movies/update_spinner.mng'
-TMPDIR='/tmp'
-TMPNAME='tmp-%03i.png'
+SRC='img/reload.png'
+TMPDIR='../../src/qt/res/movies/'
+TMPNAME='spinner-%03i.png'
 NUMFRAMES=35
 FRAMERATE=10.0
 CONVERT='convert'
@@ -36,8 +35,4 @@ for frame in xrange(NUMFRAMES):
     im_new.save(outfile, 'png')
     frame_files.append(outfile)
 
-p = Popen([CONVERT, "-delay", str(FRAMERATE), "-dispose", "2"] + frame_files + [DST])
-p.communicate()
-
-