systemtap prototype #3.1

- demonstrates partial parsing of hypothetical systemtap script
  language using hand-written simpe LL(1) recursive-descent parser
  and similar little lexer: parse.cxx, parse.h
- semantic analysis in stapfile.cxx, driven from semtest.cxx
- examples under testsuite
- "probe", "global", "function" top-level constructs parsed
  no provider-oriented syntax provided yet
- use autotools-style configure; make; make check
- to see parse tree dump, use stdin: echo 'SCRIPT FRAGMENT' | ./parsetest
- to see type inference results, use stdin: echo 'SCRIPT FRAGMENT' | ./semtest