Revert "Do not use htmlspecialchars in widgets"

This reverts commit 2ff43abcf5860f4002d4fbb2aee930b22ab93ea6.

`Widget::escape()' does not exist. But `Widget::view()::espcae()' does.
Revert "Do not use htmlspecialchars in view scripts"

This reverts commit 607aa9b203377126b399667cd0b10c80d75e04b7.

`Perfdata::escape()' does not exist. But `Perfdata::view::escape()' does.