Big endian for arm.winedbg and addn randomart in rax2 -k

r_asm: Add support for big endian arm.winedbg
rax2: Add -k randomart to rax2, -k is now -B
rax2: Handle multiple flags on a single argument
rax2: update manpage
Merge branch 'master' of github.com:radare/radare2