Make rect rendering use W+H characters instead of W*H+H characters

[NicEastvillage]

RLDojo renders a rectangle that ends up requiring too long a string. This change drastically reduces the number of characters used in rectangle rendering by only filling one line.

For example, instead of

********\n
********\n
********\n
********\n

we now do

********\n
\n
\n
\n