Renamed icons with leading dot

[enumag]

It's common practice to have some code in .htaccess that prevents autoloading of all files with a leading dot (like .htaccess, .gitignore, .gitattributes, .travis.yml and so on). Because of that KCFinder couldn't load some icons in my case. I think it would be better not to use such file names so here is a fix - I've just replaced the leading dots with underscores.

[HenkerX64]

nice fix, thanks