Security:
- CVE-2018-18356: Use-after-free in Skia
- CVE-2019-5785: Integer overflow in Skia
- CVE-2018-18335: Buffer overflow in Skia with accelerated Canvas 2D
- CVE-2018-18509: S/MIME signature spoofing
Other fixes:
- CalDav access to some servers not working
Signed-off-by: Pierre-Yves <pyu@riseup.net>