Addition: Statistics methods to the Page Model

Adds Page->getTotalPageViews($date = null) &
Page->getPageStatistics($limit = 20) statistic methods to the Page
model, there is no way to 'legally' get this data for Pages at the
moment, where as the is for Files via the File->getDownloadStatistics()
& File->getTotalDownloads().
Addition: on_file_delete event dispatch

Strange? There must be reasoning for this not being implmented, however
if there isn't, I've added the event to the file models delete method,
it also allows cancellation of the deletion.
Addition: on_page_trash event dispatch

Probably pencilled in for 5.7.0 anyway.
modified urlify (used when creating page paths) to use concrete config for remove word list.
stubbed out 5.7.0 upgrade script, added but commented out single page addition for seo exclude words
Reserved Words.
finished up the seo excluded words
added help text and corrected form help
added a check to the private message system so it does not send error emails back to the sender if that email message is a send failure.
config tweak
Merge branch '5.7.0' of github.com:concrete5/concrete5 into 5.7.0
Merge pull request #792 from olsgreen/on-file-delete

Addition: on_file_delete event dispatch
dynamic sort by for page list
Add attachments to mail helper.
Merge branch '4.7.0' of https://github.com/concrete5/concrete5 into 5.7.0
escape value in css inspector
added mysqlt datadict to adodb
Merge pull request #868 from Remo/escape-custom-css-styles

escape value in css inspector
Merge pull request #867 from Remo/5.7-sortby-call

dynamic sort by for page list
Merge pull request #791 from olsgreen/page-total-views

Addition: Statistics methods to the Page Model