Rearranged var layout to include function definitions

The following is the layout of vars
nil [00000000000000000000000000000|000]
num [          double num         |001]
bfn [   var f(t)    |             |010]
sfn [  var f(a, s)  |  tbl scope  |011]
str [  off  |  len  |   str str   |100]
fn  [  tbl scope  |c|    fn fn    |101]
tbl [   tbl tbl   |c|             |110]
obj [   tbl obj   |c|             |111]

Layout for tables       Layout for functions
[       ref       ]     [       ref       ]
[   tbl tail    |c]     [    str bcode    ]
[  nils  |  len   ]     [ acount | vcount ]
[       mask      ]     [ fcount | stack  ]
[     keys      |r]     [      fn fns     ]
[     vars      |r]     [     var vars    ]