- support create a segy from a sub-volume array and a full volume segy header, using `cigsegy.create_by_sharing_header('sub.segy', 'header-full.segy', dsub, iline=, xline=, istep=, xstep=, offset=)`
- add a function `Pysegy.cut(outsegy, ...)` to cut a sub-volume from the full segy file and save to a segy file
- for all functions to create a segy file, you can use `custom_info` to custom the first 12 lines of textual header
- support the segy files with inline first order, (i.e., the order is time->inline->crossline, the default is time->crossline->inline)
- fixed a bug of `scan()` function
- add a function `tools.plot_region(...)` to plot the region of a segy file