Fixed unicode and max message length issues

Increased limit of 255 US-ASCII characters or 85 unicode characters per
note message to a max of 21845 characters. Made all tables have UTF-8
charset by default so that databaseManager.php can just set client
charset to UTF-8 for all queries and so that we allow email addresses
with quoted or escaped characters outside of US-ASCII. Prevent HTML
injection for nicknames and email addresses. Fix all magic-quoted
strings. Compose sticky note is slightly less pale. Enable tooltip over
Submit note button when button is being disabled following a previous
submission. Fixed the Register button not getting disabled on the
Register page.
Backup cookie token generator; whitespace changes

Use Mersenne Twister as a less secure but ubiquitous fallback for cookie
token generation if the php_openssl extension is not available.
Re-enable pre-wrap white-space and do not trim anything entered into the
compose note so that exact spacing that was entered into the compose
note is preserved when displayed as a regular note. Maximize amount of
characters per note by storing notes unescaped in database and then
escaping HTML and replacing newlines with line breaks in
index.php#constructNoteElement. Grow board when compose note autosizes
beyond board's height.