#125 Enrich export options

[Justin Bradley]

There has been a request to augment the export facilities on LabTrove to address a number of points.

1) Be able to export the entire blog dataset for use in archival, backup and potentially migration (import) into other system.
2) Be able to export specific parts of a dataset for inclusion elsewhere, or for archival, specifically date ranges of posts, or posts under a given section.
3) Have exported data in PDF form, for easy consumption off-line, or for producing reports/papers, or for printing.

These can be achieved by a number of change sets, which will be summarised here but tracked individually under separate tickets.

1) Add the facility to export as xml as well as html (xml export can already be done on a per post basis).
2) Extend search, so results can be limited to a date range, section, specific post title/id (etc).
3) Allow exports to be based on search results, so specific parts of a LabTrove instance can be exported as required. Where these parts may include a single post, a subset of the entire post-set, or all of the posts.
4) Exports need to be configurable to optionally include attachments, comments, revisions, and to follow linked posts to an arbitrary level.
5) A PDF rendering service needs to be developed, this will be able to take an export 'bundle' and return a single PDF representing it. This service should be standalone so we can host a public one, or instances can be hosted alongside a LabTrove. The service needs to have the export bundle pushed to it, so it doesn't encounter issues with firewall access (like the current PNG converter).
6) Produce an importer, so exported bundles can be imported into a fresh LabTrove instance.

#5 and #6 will come after 1-4.

[Justin Bradley]

7) Allow filtering of the items to be exported by using the existing filtering model implemented by users selecting sections etc from the right hand menus. These may well be searches behind the scenes.

A point to note. The export user interface/dialogue should include a confirmation/review stage where the user can see what items have satisfied their filtering/query. Then they can choose the output format(s) and press a 'go' button. Exports can be large and take some times to compile.

[Justin Bradley]

Parts 2 and 3 are now done, caveat any issues raised by testing. svn r442