merge function

[M] = merge(m1,m2) Takes 2 matrices with elements (including NaN) and combines them

Takes 2 2-dimensional matrices with (NaN) elements and combines them, replacing NaN with real values from either matrix. If sizes dont match, expands the matrices from point (1,1) . If the element of m1 is a number and the same element of m2 is also a number, pick from m1 over m2.

Useful for working with matrices with incomplete data that could complete one another.