// Go to menue:
// find->find in files
// Switch on reg_ex button
// Find:
^(.*)$
// Where:
c:\your_folder\,*.php,*.phtml,*.js,*.inc,*.html, -*/folder_to_exclude/*

// Then click on the find button
// Be careful to not click on Replace!!!
// On the bottom line of your search result you'll find something like:
// 21342 matches in 124 files = your lines of code