Feat/review year month week

[hotoo]

fixed https://github.com/hotoo/calendar-vim/issues/1

• Yearly file.
• Monthly file
• Weekly file
• Add g:calendar_weeknm = 6 to display week number W01
• Add g:calenday_diary_path_pattern to define yearly file path.
• Add g:calenday_weekly_path_pattern to define yearly file path.
• Add g:calenday_monthly_path_pattern to define yearly file path.
• Add g:calenday_yearly_path_pattern to define yearly file path.
• Add g:calendar_focus_type to set difference focus types.
• Add g:calendar_wnmruler to set weeknm ruler.

[hotoo]

fixed #33

close #40

[hotoo]

@mattn review this PR please.