Comment Truncation Overhaul, and Server Delete Fix

Filled out the comment truncation code in comments.js getFormattedCommentContent, to now first limit lines to new option textTruncateLines (3), except where text exceeds new option textTruncateLength (330). Where only small amount of extra text (beyond max), allow up to next century boundary (400), except where contains new line. In addition, handle toggling of truncated text with standard comments.js click handler, with new clickable span toggle (instead of link) added at same time, which produces dramatic performance improvement. Also fixed cache related bug in views_api.py in on_delete_comment, and improved related code, defining constant CACHE_TIMEOUT.