Partial implement of iCalendar converter
Fix docstring
Include year part in default summary line

This is preparation for summary buffer as a search result
Add new command mhc-search "/"
Show grace message if mhc-search returns no match
New functions to move week frame of mhc-date

mhc-date-ww-first, mhc-date-ww-last: moves date to the first/last date of
current week.
Refactoring
Update README
Adjust elisp file format
Hide garbage comments from RDoc
More solid converter from iCalendar to MHC
Add some DB interface to MHC for two-way sync
Emit better sync error message
Less progress message on sync
Fix time zone converter
Abort if sync process has too many items to sync
Fix off-by-one error on calculation of X-SC-Duration
Add X-SC-Recurrence/Mission-Tag into iCaledar using X-property
Introduce fine-grained sync control

Now sync-strategy handles 16 states, formerly used to 9.
Add tests