Fixed #280. Possibly #257 and #290 as well.
There is a possible bug in glibc (as mentioned here:
https://github.com/ioquake/jedi-academy/commit/d6bc68d63259234b83ceaec9464cebd2aa188374)
where the library is not unloaded properly. This causes global variables
to retain their previous values if the library is then reloaded. By
defaulting symbols to hidden, the library can be unloaded properly. This
may also fix a number of other issues as mentioned above.