Add icons to "select-all" and "select-none" buttons in the journal

Signed-off-by: Walter Bender <walter@sugarlabs.org>
The .view insensitive should not have the same grey than the entry

Signed-off-by: Gonzalo Odiard <gonzalo@laptop.org>
Merge pull request #8 from godiard/journal_multiselection-try2

Add icons for the Journal multiselection toolbar
Release 0.99.1
GTK3 theme 72%, fix chekboxes

- We had 'indicator-size' harcoded to 26px.  Now is a proper number
  for sugar-72 theme.

- Provide new SVG files for the checkbox states, for sugar-72 .  Those
  were optimized with SVGO https://github.com/svg/svgo

- Reorder the assets in directories 'assets/100' and 'assets/72'.  The
  Makefile takes care of copying the correct SVG files to the build
  directory.

Fixes #4092 .
GTK3 theme 72%, fix sliders

- Variable scale_trough_margin was harcoded for both themes.  Now is a
  proper number for sugar-72 theme.

- Provide new SVG files for the slider assets, for sugar-72 .
GTK3 theme 72%, fix radio buttons

- Provide new SVG files for the radiobutton states, for sugar-72 .