add io_seek, operate on bytes instead of strings

[enricozb]

• Adds a SEEK io operation.
• replace READ_LINE and READ_CHAR with just a READ, taking in the number of bytes to be read.
• READ and WRITE now operate on lists of bytes

[HigherOrderBot]

Perf run for 5bbb1f5:

compiled
========

file            runtime         main            (local)       
==============================================================
sort_bitonic    c                        5.69s           3.09s
                cuda                     0.24s           0.23s
--------------------------------------------------------------
sum_rec         c                        1.36s           1.43s
                cuda                     0.15s           0.14s
--------------------------------------------------------------
sum_tree        c                        0.12s           0.11s
                cuda                     0.10s           0.10s
--------------------------------------------------------------
tuples          c                        3.80s           4.18s
                cuda                   timeout         timeout
--------------------------------------------------------------

interpreted
===========

file            runtime         main            (local)       
==============================================================
sort_bitonic    c                        4.77s           4.04s
                cuda                     0.24s           0.24s
                rust                   timeout         timeout
--------------------------------------------------------------
sum_rec         c                        1.66s           1.97s
                cuda                     0.14s           0.13s
                rust                    14.02s          14.13s
--------------------------------------------------------------
sum_tree        c                        0.39s           0.17s
                cuda                     0.08s           0.08s
                rust                     0.83s           0.84s
--------------------------------------------------------------
tuples          c                        3.69s           3.65s
                cuda                   timeout         timeout
                rust                     3.64s           3.78s
--------------------------------------------------------------