new icons for linux, etc.

- new xpm resources for different linux window managers
- new png files for autoresizing on different linux window managers
- favicon with new logo
- window .ico with new logo
- updated debian package script
- updated changelog
Merge pull request #2650 from jonasschnelli/new_xpm_icons

new resources for linux software package managers
Docs Markdown Cleanup
Merge pull request #2666 from super3/master

Doc Cleanup with Markdown
Add a few data-driven tests for SIGHASH_ANYONECANPAY
Merge pull request #2678 from TheBlueMatt/master

Add a few data-driven tests for SIGHASH_ANYONECANPAY
Update links in build-osx.md

Add link to Github for Mac
Update link to HomeBrew
gitian deps-win32.yml needs psmisc package for killall to end the build
Merge pull request #2681 from wtogami/gitianfix

gitian deps-win32.yml needs psmisc package for killall to end the build
Merge pull request #2680 from fanquake/patch-1

Update links in build-osx.md