Tidy up "interfaces.php" XHTML

Add summary to TABLE tags
Add missing opening and closing cell tags in TR tag
Tidy up closing FONT tag
Remove duplicate closing TD tag and duplicate closing TR tag
Add missing opening TR tag
Remove duplicate width statement
Add missing closing DIV tag
Remove tags within comment block
Merge pull request #593 from ExolonDX/branch_03

Tidy up "interfaces.php" XHTML