Fix coding guidelines incoherences. Code should match PSR1/2 now, and
php-cs is set to check it on each commit.
Also fixed the Git hook to take into account only added, modified,
copied and renamed files (preventing errors when trying to check deleted
files).
Closes#1260.
1) optimization: _xxxChilds: slice whole items array BEFORE converting to output objects
2) fix with special chars in items title.
Some players stops after receiving some special chars.
Don't know which exactly char is wrong, replace all special chars to '-'