[book, form] include complete example of self-posted form with custom field/widget + minor other changes

backport stable

[datafeed] don't raise bad config error on source initialization

[schema] closes #1816439: RQLConstraint does not take variable U into account

[web form] avoid mis-formated warning for _cw_fields

[doc, hook] more backport of syt mbox documentation

[book, ldap] backport some doc from my mailbox

[book] fix some urls

[book, forms] talk about cnx.use_web_compatible_request instead of custom monkey-patching

[book] drop gae from the book

[book, admin] include some fixes done by auc in an email to me

[book] fix some rest/sphinx errors

[repo test] fix broken tests

closes #1784285: [rql2sql] crash when using a relation for inner and outer join

[range facet] closes #1806937: simply retrieve min/max values when computing vocabulary/possible_values, this is enough

[facet] fix facet values update, broken by 7626:56300bec75f8

[facet slider] quote attribute value, else may break with earlier jquery

[facets] use unique dom id

[facet] with rql path facet rel may be None, handle it

[facet] closes #1806932: test and fix facet bug w/ having query (need rql update)

[ajax js loading] when everything is already loaded, don't do anything

backport stable

[IE, plot] ship with jqplot'excanvas version (include http://code.google.com/p/explorercanvas/issues/detail?id=82 for instance)

[etwist, modconcat] closes #1806935: directly write data, don't put the whole concatenated thing in memory

[etwist] clear ui cache at server startup time. Closes #1806933 this avoid pb when cubicweb/cubes provide new version of some js/css and also accumulating junk in the cache directories

[facet] closes #1806931: new facet type, based on arbitrary rql path

[selectors, test] remove duplicated test and add some for relation_possible selector w/ rqlst

[repository] catch Exception instead of everything

[facet] fix argument inversion in date range facet

[facetbox] put the facet box in a box