Correct an e-mail in the change log

Correct the e-mail for Alex Melbourne from 'a.melbourne@uea.ac.uk' to
'alex_melbourne@hotmail.co.uk'.

The original e-mail is the result from a copy-and-paste action at the
start of the project. The e-mail address is an academic one and is
wrong.
Author logical operators for the `SMatrix` type

Write the functions `operator==`, and `operator!=` for the structure
`SMatrix`.

Comparison is one of the fundamental operations of a matrix.

For the sake of creating "complex" areas of code, the function
`operator!=` simply returns the logical inverse of the `operator==`
function through the principle that, if two entities are equal, they
cannot be unequal.