simplify add message form

by removing the "tags" option as well as the "add" (file upload) option.
now, only already uploaded files can be attached to a message.
set closed tasklists visually apart in project->tasks
remove tags from editmessageform
tree gets project color code

not milestones or timetracker
remove gradient from bg in favor of solid color
fix notice in filemanager -> list view
fix notice
milestones can be async deleted

and remove paging from the file editor
Fehler im Datepicker behoben. Nun kann der 1.9.2013 korrekt gewählt werden.
la
applied the changes in mycalendar.js to mycalendar_orig.js, too.
fixed wrong jsval includes in header.tpl
preparing for basic auth in managetask.php
implemented auth request
implemented login using given credentials. needs testing now.
added show_long parameter to getIcal method to allow showing tasks only on due date
added action "icalshort" for shortened task display in usual calendar software
added commentation
added hint for usage of icalshort to auth message
Corrections and addition by Sebastián Di Luise (thanks!)