byte access in memory
changed pprint to pwrite (without newline), made "." part of library
memory access protection

Read operations limited to data segment as defined per linker, write operations
limited to memory defined in interpreter.h
Will need to be changed for peripheral access  on embedded targets
enable tracing for all targets
iset doc
fix lit
add memory read protection to parsenum
no underscores, just hyphens in names, also discovered problem with
recursion

tail recursion is too greedy, in that it will dynamically recall any
quotations it is defined in (even inline quotations) making it useless
for use in combinators