* improvement: reading from a TWO-WAY-STREAM does not touch the output
stream anymore making it thread safe to have a concurrent reader and
a writer, for instance, in a pipe.
* improvement: GET-SETF-EXPANDER avoids adding bindings for constant
arguments, making compiler-macros for SETF-functions able to inspect
their constant arguments.
* improvement: reading from a TWO-WAY-STREAM does not touch the output
stream anymore making it thread safe to have a concurrent reader and
a writer, for instance, in a pipe.
* improvement: GET-SETF-EXPANDER avoids adding bindings for constant
arguments, making compiler-macros for SETF-functions able to inspect
their constant arguments.