Replace "Shape" with "Pair" to use for more general purpose.
sliceMatrix is used to represent row vector or column vector of an arbitary matrix.
Typo: Replace "Row" with "Rows".
Fix: Remove a needless return statement.
Fix: Matrix interface requires Rows and Cols.
Add test cases for sliceMatrix.
Implement mutable/slice/matrix.go, but some bugs exist.
Pass tests for sliceMatrix.
Merge branch 'feature/matrix-slice'