Add "vector" constructor methods taking ring as input

[d-torrance]

Currently, we can do the following for matrices and it works as expected:

i1 : matrix(QQ, {{1, 2}, {3, 4}})

o1 = | 1 2 |
     | 3 4 |

              2       2
o1 : Matrix QQ  <-- QQ

But it doesn't work for vectors:

i2 : vector(QQ, {1, 2, 3})
stdio:2:6:(3): error: no method found for applying vector to:
     argument 1 :  QQ (of class Ring)
     argument 2 :  {1, 2, 3} (of class List)

We add this functionality. In particular, given a Ring (or RingFamily, so we catch RR, CC, and RRi) and a matrix, list, number, or ring element, we construct an element of the appropriate free module over that ring:

i1 : vector(QQ, {1, 2, 3})

o1 = | 1 |
     | 2 |
     | 3 |

       3
o1 : QQ

[mahrud]

I had convinced myself that vector(QQ^3, {1, 2, 3}) works and it's just as good as vector(QQ, {1, 2, 3}), but I see the appeal.