Deprecated wp_specialchars() in favor of…

Deprecated wp_specialchars() in favor of esc_html() (also: esc_html__() and esc_html_e()). Using wp_specialchars() with more than one param works for backwards compat. Also, esc_html() (or wp_specialchars() with one param) escapes quotes, just like esc_attr(). This buys security for plugin authors who were mistakenly using a one-param wp_specialchars() call in an HTML attribute. See this wp-hackers message for more detail.