[packages] transmission: update to 2.76

git-svn-id: svn://svn.openwrt.org/openwrt/packages@35084 3c298f89-4303-0410-b956-a3cf2f4a3e73
[packages] rtl-sdr: New package, software defined radio with RTL2832U dongle

git-svn-id: svn://svn.openwrt.org/openwrt/packages@35085 3c298f89-4303-0410-b956-a3cf2f4a3e73