rewrite the analyzer entirely
analyzer no longer requires envirohment.h
cosmetic fix
add list convenience utilities
revise analyzer API
complete refactor analyzer
remove forward declarations of obsolete classes
rename variable -> variable_t; for the sake of using the name in defining alias for shared_ptr
write some small definitions in the header
fixed the types of arguments in scope#scope
change the analyzer API: find/add methods are in scope class
update analyzer.cpp: keep track of the API changes
remove unused include
change the ownerships of args/locals
fix typo
refactor: add read_file function
reach analysis phase via helmold command