Fix compiler error.
Merge pull request #19 from nbaum/master

Add stub for KTLProjectManager::copyFilesAndFolders from kdevplatform.

This new method has appeared first in kdevplatform 1.4.90.

The releases 1.4.0 and 1.4.1 of kdevplatform have
#define KDEVELOP_PLUGIN_VERSION 14
 while the release 1.4.90 has
#define KDEVELOP_PLUGIN_VERSION 15
 so the check for proper KDevelop / KDevPlatform version should be:
# if KDEV_PLUGIN_VERSION >= 15

After adding that check, this pull request is ready for merge in my opinion.