Merge branch 'develop' of https://github.com/shokichi/dcpam_rb into bug_fix
Typo
Enable to work if not defined Opt
Add some method

- rename to diurnal from mask_diurnal
- create mask_diurnal
- create mask_night
Add some methods

- []
- []=
- set_axis
- delete
- print
- to_gphys
- mask_day_fix
- mask_night_fix
Merge branch 'bug_fix'