fix handling of escaped characters like ' " & < >
fix handling of escaped characters like ' " & < >

R=r
http://go/go-review/1013007

pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,tv42/old-go,apparentlymart/golang,nightlyone/golang,tv42/old-go,h8liu/golang,tv42/old-go,nightlyone/golang,h8liu/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,ssrl/go,nightlyone/golang,gnanderson/go,bdwalton/debian-golang,tianon/debian-golang,bdwalton/debian-golang,gnanderson/go,h8liu/golang,h8liu/golang,bdwalton/debian-golang,apparentlymart/golang,tv42/old-go,tv42/old-go,tianon/debian-golang,pombredanne/go-deleteme,dsriram/golang,dsriram/golang,gnanderson/go,dsriram/golang,tv42/old-go,tianon/debian-golang,nightlyone/golang,bdwalton/debian-golang,bdwalton/debian-golang,tianon/debian-golang,ssrl/go,bdwalton/debian-golang,pombredanne/go-deleteme,ssrl/go,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,dsriram/golang,ssrl/go,pombredanne/go-deleteme,dsriram/golang,h8liu/golang,ssrl/go,tianon/debian-golang,apparentlymart/golang,apparentlymart/golang,tianon/debian-golang,dsriram/golang,gnanderson/go,tianon/debian-golang,h8liu/golang,gnanderson/go,nightlyone/golang,h8liu/golang,ssrl/go,gnanderson/go,nightlyone/golang,gnanderson/go,ssrl/go,tianon/debian-golang,apparentlymart/golang,bdwalton/debian-golang,nightlyone/golang,bdwalton/debian-golang