Improve collapsed style

Currently if a user was to collapse a table with a thead, the bottom
corners have no boarder radius, but the container does leaving it
looking out of place.
This commit adds the thead_collapsed class to the .thead (if present)
when collapsed or when set as collapsed from a cookie.
Fix #377 Installer suggests incorrect cookie domain

The logic for this was backwards. If `my_inet_pton($cookiedomain)` returns false, or `strpos($cookiedomain, '.')` returns anything but true, we have an invalid cookie domain.
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Update index.php
fixes #484 - "Search for Users" in modcp
use $mybb->get_input(...) instead of $mybb->input[...]
Compare with current MyBB version code

We don't want a static version number when we don't need one. ;)
Merge pull request #444 from PenguinPaul/fix-185

Fixes #185: Slow install
Update development standards for c1ed270
Fixes #344 Debug has incomplete information
Merge pull request #515 from PaulBender/fix-feature-344

Fixes #344 Debug has incomplete information
Merge pull request #224 from JordanMussi/feature-improve-collapsed-style

Improve collapsed style
Working on jQuery Conversion #251
The Who Posted? pop-up now works
Working on #251 jQuery Conversion

All popupWindow calls have been fixed in the AdminCP.
Fixed a bug related to IP address printing the ACP (noticed while fixing
modals).
The IP address info is now output from the ACP instead of being output
from modcp.php?action=iplookup&address=X
Fixes #458 Incorrect msg when soft deleting post
Merge pull request #501 from ATofighi/fix-484

Fixes #484 - "Search for Users" in modcp
I can confirm this PR works fine.
Merge pull request #391 from nmalcolm/fix-377

Fix #377 Installer suggests incorrect cookie domain
Merge pull request #409 from PaulBender/feature-replyownthread

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