Allow for non .ics extensions on calendar entries.

* Davmail stores its calendar entries as UUID.EML and was previously unusable.
Merge branch 'master' of https://github.com/coroa/org-caldav
Fix/extend doc strings.
Require 'cl during compile.
Add debug output for different calendars.
Merge branch 'coroa-master'

* coroa-master:
  Add debug output for different calendars.
  Require 'cl during compile.
  Fix/extend doc strings.
  org-caldav-sync-result-print-entries: Fix overzealous tabify
  org-caldav-calendars: Support multiple calendars
  org-caldav-inbox: Enable specifying a heading, where to add new entries
  org-caldav-select-tags: Add variable to sync only entries with specific tags
  org-caldav-sync-result-print-entries: Insert "None" without entries
  org-caldav-cleanup-ics-description: Properly clean ranged timestamps from description
Update README.
Merge pull request #35 from willkelly/master

Allow for non .ics extensions on calendar entries.
Set 'print-length' and 'print-level' to nil when saving sync state (issue #37).

(org-caldav-save-sync-state): Explicitly set `print-length' and
`print-level' to nil, otherwise we might not save the full list.
Merge branch 'master' of https://github.com/dengste/org-caldav
typo
updated
Readme update yet again.
Readme update. Grrr.
Introduce with-calendar macro to simplify calendar switching
Fix org-caldav-empty-calendar handling with multiple calendars

org-caldav-empty-calendar needs to be reset on switching to another
calendar.