new windows and linux icons

- new windows .ico contains multiple resolutions up to 256px
- new testnet (green) icon
- new png icon for llinux, etc.
- new doxygen icon
- changed the assets-attribution.txt

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>

doc/assets-attribution.txt

@@ -1,5 +1,8 @@
 Icon: src/qt/res/icons/clock*.png, src/qt/res/icons/tx*.png,
-      src/qt/res/src/*.svg
+      src/qt/res/src/clock_green.svg, src/qt/res/src/clock1.svg
+	  src/qt/res/src/clock2.svg, src/qt/res/src/clock3.svg
+	  src/qt/res/src/clock4.svg, src/qt/res/src/clock5.svg
+	  src/qt/res/src/inout.svg, src/qt/res/src/questionmark.svg
 Designer: Wladimir van der Laan
 License: MIT
 
@@ -35,7 +38,7 @@ Designer: http://www.everaldo.com
 Icon Pack: Crystal SVG
 License: LGPL
 
-Icon: src/qt/res/icons/bitcoin.png, src/qt/res/icons/toolbar.png
+Icon: src/qt/res/icons/toolbar.png
 Designer: Bitboy (optimized for 16x16 by Wladimir van der Laan)
 License: Public Domain
 Site: https://bitcointalk.org/?topic=1756.0
@@ -56,6 +59,8 @@ Designer: Vignoni David
 Site: http://www.oxygen-icons.org/
 License: Oxygen icon theme is dual licensed. You may copy it under the Creative Common Attribution-ShareAlike 3.0 License or the GNU Library General Public License.
 
-Icon: src/qt/res/icons/bitcoin.icns, src/qt/res/icons/bitcoin.svg
+Icon: src/qt/res/icons/bitcoin.icns, src/qt/res/src/bitcoin.svg,
-Designer: Jonas Schnelli (original bitcoin logo from Bitboy)
+      src/qt/res/src/bitcoin.ico, src/qt/res/src/bitcoin.png,
+      src/qt/res/src/bitcoin_testnet.png, docs/bitcoin_logo_doxygen.png
+Designer: Jonas Schnelli (based on the original bitcoin logo from Bitboy)
 License: MIT