Use sv_t instead of raw char*

We're storing them as sv_t's anyway, we're fucked with regards to
indirection.  Thus, let's be nice to ourselves, and deal with the
structures.  We get the size of the structure for free anyway!

alisp.h

@@ -78,7 +78,7 @@ typedef struct
 
 u64 djb2(sv_t string);
 void sym_table_init(sym_table_t *table);
-char *sym_table_find(sym_table_t *table, sv_t sv);
+sv_t *sym_table_find(sym_table_t *table, sv_t sv);
 void sym_table_cleanup(sym_table_t *table);
 
 /// Basic defintions for a Lisp
@@ -115,7 +115,7 @@ lisp_t *intern(sys_t *sys, sv_t sv);
 lisp_t *cons(sys_t *sys, lisp_t *car, lisp_t *cdr);
 
 i64 as_int(lisp_t *);
-char *as_sym(lisp_t *);
+sv_t *as_sym(lisp_t *);
 cons_t *as_cons(lisp_t *);
 void *as_vec(lisp_t *);
 
@@ -160,7 +160,7 @@ enum Mask
 tag_t get_tag(lisp_t *lisp);
 
 lisp_t *tag_int(i64 i);
-lisp_t *tag_sym(char *str);
+lisp_t *tag_sym(sv_t *sv);
 lisp_t *tag_cons(cons_t *cons);
 lisp_t *tag_vec(lvec_t *lvec);
 

constructor.c

@@ -43,6 +43,6 @@ lisp_t *make_vec(sys_t *sys, u64 capacity)
 
 lisp_t *intern(sys_t *sys, sv_t sv)
 {
-  char *s = sym_table_find(&sys->symtable, sv);
-  return tag_sym(s);
+  sv_t *str = sym_table_find(&sys->symtable, sv);
+  return tag_sym(str);
 }

symtable.c

@@ -32,9 +32,9 @@ void sym_table_init(sym_table_t *table)
   vec_make((void **)&table->entries, table->capacity * sizeof(*table->entries));
 }
 
-char *sym_table_find(sym_table_t *table, sv_t sv)
+sv_t *sym_table_find(sym_table_t *table, sv_t sv)
 {
-  // TODO: Deal with resizing this when table->count > table->size / 2
+  // WIP: Deal with resizing this when table->count > table->size / 2
   u64 index = djb2(sv) & (table->capacity - 1);
 
   for (sv_t comp  = table->entries[index]; comp.data; index += 1,
@@ -51,7 +51,7 @@ char *sym_table_find(sym_table_t *table, sv_t sv)
     ++table->count;
   }
 
-  return table->entries[index].data;
+  return table->entries + index;
 }
 
 void sym_table_cleanup(sym_table_t *table)

tag.c

@@ -22,7 +22,7 @@ lisp_t *tag_int(i64 i)
   return TAG((u64)i, INT);
 }
 
-lisp_t *tag_sym(char *str)
+lisp_t *tag_sym(sv_t *str)
 {
   return TAG((u64)str, SYM);
 }
@@ -57,10 +57,10 @@ i64 as_int(lisp_t *obj)
       ;
 }
 
-char *as_sym(lisp_t *obj)
+sv_t *as_sym(lisp_t *obj)
 {
   assert(IS_TAG(obj, SYM));
-  return (char *)UNTAG(obj, SYM);
+  return (sv_t *)UNTAG(obj, SYM);
 }
 
 cons_t *as_cons(lisp_t *obj)