[MRG] new array and matrix functions

Convert ROOT arrays and matrices into numpy arrays and matrices.

```python

def array(arr, copy=True):                                                      
    """                                                                         
    Convert a ROOT TArray into a NumPy array.                                   
                                                                                
    Parameters                                                                  
    ----------                                                                  
                                                                                
    arr : ROOT TArray                                                           
        A ROOT TArrayD, TArrayF, TArrayL, TArrayI or TArrayS                    
                                                                                
    copy : bool, optional (default=True)                                        
        If True (the default) then copy the underlying array, otherwise         
        the NumPy array will view the same memory as the ROOT array.            
                                                                                
    Returns                                                                     
    -------                                                                     
    arr : NumPy array                                                           
        A NumPy array                                                           
                                                                                
    Examples                                                                    
    --------                                                                    
                                                                                
    >>> from root_numpy import array                                            
    >>> from ROOT import TArrayD                                                
    >>> a = TArrayD(5)                                                          
    >>> a[3] = 3.141                                                            
    >>> array(a)                                                                
    array([ 0.   ,  0.   ,  0.   ,  3.141,  0.   ])                             
                                                                                
    """

def matrix(mat):                                                                
    """                                                                         
    Convert a ROOT TMatrix into a NumPy matrix.                                 
                                                                                
    Parameters                                                                  
    ----------                                                                  
                                                                                
    mat : ROOT TMatrixT                                                         
        A ROOT TMatrixD or TMatrixF                                             
                                                                                
    Returns                                                                     
    -------                                                                     
                                                                                
    mat : numpy.matrix                                                          
        A NumPy matrix                                                          
                                                                                
    Examples                                                                    
    --------                                                                    
                                                                                
    >>> from root_numpy import matrix                                           
    >>> from ROOT import TMatrixD                                               
    >>> a = TMatrixD(4, 4)                                                      
    >>> a[1][2] = 2                                                             
    >>> matrix(a)                                                               
    matrix([[ 0.,  0.,  0.,  0.],                                               
            [ 0.,  0.,  2.,  0.],                                               
            [ 0.,  0.,  0.,  0.],                                               
            [ 0.,  0.,  0.,  0.]])                                              
       
    """
```