test => equality
test => add
test => subtract
refactoring => remove code duplication
test => dot
norm
refactoring => remove duplication norm & dot
test => add vector with different size
test => dot vector with different size
refactoring => remove code duplication
refactoring => apply pattern 'Value Object'
test => toString
refactoring => apply pattern 'Value Object'
Merge branch 'vector'
add test into all-tests.html