Reorganized ML module documentation

- fixed one BiB record
- moved algorithms overview to separate page
- added docs for some enumerations
- fixed some small documentation errors

doc/opencv.bib

@@ -106,11 +106,11 @@
   year = {1998},
   publisher = {Citeseer}
 }
-@ARTICLE{Breiman84,
-  author = {Olshen, LBJFR and Stone, Charles J},
-  title = {Classification and regression trees},
-  year = {1984},
-  journal = {Wadsworth International Group}
+@book{Breiman84,
+  title={Classification and regression trees},
+  author={Breiman, Leo and Friedman, Jerome and Stone, Charles J and Olshen, Richard A},
+  year={1984},
+  publisher={CRC press}
 }
 @INCOLLECTION{Brox2004,
   author = {Brox, Thomas and Bruhn, Andres and Papenberg, Nils and Weickert, Joachim},