Add code to read Cinema from input

This MR

• adds code to types.py to read a Cinema instance from stdin or a file according to the assignment's input format
• adds an entrypoint to cli to read a Cinema instance and print it back out again to test this

Example:

$ cat instances/assignment-example
6
9
011101111
111101111
111101111
000000000
111101111
111101111
4 4 0 1 1 0 0 0

$ cli print-instance instances/assignment-example
 ooo oooo
oooo oooo
oooo oooo

oooo oooo
oooo oooo

$ cli print-instance -
# enter input manually / redirect file to stdin
4
4
1001
1111
1011
0110
o  o
oooo
o oo
 oo 

This conflicts partially with !4 (closed) as that adds code to read an instance as well.

mentioned in merge request !4 (closed)

mentioned in merge request !7 (closed)

merged