use a right paren callback so that readlist and readbrfn don't have to duplicate reader code for comments
more tests for comment interspersing in brackets and lists
block comments
test for block comments
read sexpr comments, and ensure that the reader always reads everything at the end
Make sure to read the terminating bracket!
add more tests for the weird ways in which comments and code can interact
remove redundant cases for readlist and readbrfn
character reader
allow an optional radix for substring
tests for characters
add hexdigit
add tests for strings and escape sequences
string reader