add normalized core lang
reindent ncl.sml
add label for vars
add alpha conversion in AST
lambda in NCL need to be 'let'
Merge branch 'master' into kcfa
implement EnvStr.compareWith; rename NCL ast Lam to LetLam
add 0-CFA prototype
add language specification
re-typeset the reduction rules
move lstlisting utils to a separate file
fix language defn bug
update .gitignore to ignore LaTeX files
fix operational semantics' labeling
add normalized core language (NCL) description
fix various typo in defns
change 'mapsto' notation to ':='
change 'mapsto' notation to ':='
fix NCL.sml according to the def
rename NCL constructors