Printing errno on log_error()
Checking for null lists in list_concat()
Adding op_new() and push_op()
Starting get_address()

Needs get_identifier() to return yytext if finding an implicit symbol
Refactoring into scope.h
Making get_identifier() public
Refactoring of get_address()

Once implicit symbol table is built, this should work for all kinds of
symbols
Adding implicit symbol table for constants
Adding function call to test data
Updating tasks