Update sessions chapter in userguide
select the newly imported session in the list
Merge pull request #468 from PeterBjuhr/userguide

Update sessions chapter in userguide
for snippets, add the shortcuts to the action so they appear in the help
error handling on saving/importing sessions
move error catching out of Document, cleaner error handling; show os errno in a consistent way
pot update, nl/po update
nl
allow specifying an url on load and save of Document

this will become the current url if the action succeeds. Now save as
does not keep the (invalid) url given on save, while it is not
necessary to check e.g. writability beforehand, as was the case.
error handling on save/reload in external changes dialog
do not save and load on empty urls
oops
Problems with indent
Merge pull request #469 from PeterBjuhr/sessions

Problems with indent
dont store document if load in __init__ fails
Merge branch 'master' of github.com:wbsoft/frescobaldi
improve error handling around documents

when loading a new document fails, one is not created
the operating system error message and errno is propagated to the dialogs
naming unexistent files on the commandline still is allowed, because one
often starts editing a new document that way. (currently, the default
template handling is not yet used when a non-existent document is specified
on the commandline.)
ehrm
properly wrap some more IOErrors
upd chlog, pot, nl.po