This also fixes few clang build errors

All tests passed!

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

This reverts commit 94b97b7a.

This partly reverts commit 6ca61827.

Made the function "clipLine" to work with int64 values instead of int --- otherwise sometimes it returned wrong points coordinates, and it caused the function "line" to crash.

added improved ORB implementation, convex-convex polygon intersection, eigen2x2 low-level function ...

added COVAR_ and SORT_ enums to core.hpp; fixed many, many VS2005, VS2010 and MinGW (GCC 4.5.2) warnings

a big patch; use special proxy types (Input/OutputArray, Input/OutputArrayOfArrays) for passing in vectors, matrices etc.