Build the basic capability of process editing about dynacut

[xjtuwxg]

Here I listed some sample outputs of the tool:

1/7:

## check out the memory mapping from the process image, insert the number of pages, 
## and list the mapped memory in the following line (a combination of crit x  mems and rss).
$ <your tool> x checkpoint mapping
	55daea6a4000-55daea6a5000     1      r-- /home/xiaoguang/works/criu/test/test.simple/simple-123
	55daea6a5000-55daea6a6000     1      r-x /home/xiaoguang/works/criu/test/test.simple/simple-123 + 0x1000
        55daea6a5000 / 1
        ... ...
        55daeae1b000-55daeae3c000     33    rw-
        55daeae1b000 / 1,  55daeae3a000 / 1
        ... ...

2/7 - 4/7:
The tool can take the parameters of code or stack or heap to output the following information:

## $ <your tool> x checkpoint mapping code|stack|heap
$ <your tool> x checkpoint mapping code
	55daea6a5000-55daea6a6000     1      r-x /home/xiaoguang/works/criu/test/test.simple/simple-123 + 0x1000
        55daea6a5000 / 1
$ <your tool> x checkpoint mapping stack
        7ffe201eb000-7ffe2020c000         33    rw- [stack]
        7ffe20209000 / 3

5/7:

## read a variable, given the offset of that variable in binary, read its value in the process image
$ <your tool> r checkpoint <offset-in-binary>

## write a variable, given the offset of that variable in binary, read its value in the process image
$ <your tool> w checkpoint <offset-in-binary>  <new value>

6/7:

$ <your tool> c checkpoint vma 0x1000 4
success: 0x1000 - 0x5000 inserted

$ <your tool> x checkpoint mapping
        0x1000 - 0x5000                           4      rw
	55daea6a4000-55daea6a5000     1      r-- /home/xiaoguang/works/criu/test/test.simple/simple-123

7/7:

$ <your tool> dis checkpoint
    1000:       48 83 ec 08             sub    $0x8,%rsp
    1004:       48 8b 05 dd 2f 00 00    mov    0x2fdd(%rip),%rax
    ... ...