Move functions to library file

Signed-off-by: Marc Delisle <marc@infomarc.info>
Refactor: new PMA_getHtmlForDisplayedExportFooter()

Signed-off-by: Marc Delisle <marc@infomarc.info>
Refactor: new PMA_getMemoryLimitForExport()

Signed-off-by: Marc Delisle <marc@infomarc.info>
Merge branch 'master' of https://github.com/phpmyadmin/phpmyadmin