io cache and write changes

[0x000018a0]> wc?
Usage: wc[ir*?]
 wc       list all write changes
 wc*      "" in radare commands
 wcr      reset all write changes in cache
 wci      commit write cache
NOTE: Needs io.cache=true
[0x000018a0]> e io.cache=true
[0x000018a0]> wx 9090
[0x000018a0]> wc
addr=0x000018a0 size=2
[0x000018a0]> wc*
wx 9090 @ 0x000018a0
[0x000018a0]> wci
r_io_write: cannot write on fd 3
[0x000018a0]> wcr
[0x000018a0]> wc
[0x000018a0]>
