Free the utf8Text according to the comment in Tesseract that “The recognized text is returned as a char* which is coded as UTF8 and must be freed with the delete [] operator.”.
Move all freeing memory job to dealloc.
Add freeing of _pixels and _tesseract itself.
Add a deprecated warning for - (void)clear.
Revert "Add a deprecated warning for - (void)clear."

This reverts commit 671a99d638a81239a9dffc51516f42e134a4b531.
Add a deprecated warning for - (void)clear.
2.1 version
memory leak solved
clear is deprecated. Use dealloc.
warning strlen solved