feat+fix: make compiler STRONGAAA

- FEAT: add source code length field in `fzl_reader_t` struct
- FIX: check name, lpair (lparen) and rpair (rparen) when lexing call
- FIX: check string literal termination
- FIX: increment position even on empty string to prevent infinite
lexing loop
- FIX: add string terminator in `fzl_mktoken` when allocating space for
string value
- FIX: add check for errors in recursevly called `walk`
- FIX: change source code holder from stack-stored `char[8192]` to
dynamically allocated with actual file size holder
- FIX: correct constant hasing util to hash actual string value instead
of link

src/compiler/fzl_token.c

@@ -5,8 +5,9 @@
 fzl_token_t *fzl_mktoken(const fzl_toktype_t type, uint16_t from, uint16_t to,
                          void *value, size_t value_len)
 {
-  void *valholder = malloc(value_len);
+  char *valholder = malloc(value_len + 1);
   memcpy(valholder, value, value_len);
+  valholder[value_len] = '\0';
 
   fzl_token_t *token = malloc(sizeof(fzl_token_t));
   token->type = type;