Untangle the lexer and interpreter thread state.
Fix the file and line number error reporting, getting rid of
Xsrcfile instruction, as the whole code block can only come
from a single file, stuff the source file in slot[1] of the
code block instead.
Remove limitations for globber (path element limits)
and be more intelligent about handling globbing by
inserting Xglob instruction only when needed and not
run it over every Xsimple argument list.
Remove fragile ndot magic and make it explicit by adding
the -q flag to . builtin command.
Add -b flag for full compilation.
Make exitnext() smart, so we can speculate thru rcmain and
avoid the fork().
Get rid of all print(2) format functions and use io
instead.
Improve the io library, adding rstr() to handle tokenization,
which allows us to look ahead in the already read buffer
for the terminators, avoiding alot of string copies.
Auto indent pcmd(), to make line number reporting more usefull.
Implement here documents properly, so they can work everywhere.
