Fix shift/reduce conflict

[vyorkin]

** Conflict (shift/reduce) in state 143.
** Token involved: TYPE
** This state is reached from main after reading:

LET ty_dec 

** The derivations that appear below have the following common factor:
** (The question mark symbol (?) represents the spot where the derivations begin to differ.)

main 
expr EOF 
local 
LET decs IN expr_seq END 
    list(dec) 
    (?)

** In state 143, looking ahead at TYPE, reducing production
** nonempty_list(loc(ty_dec)) -> ty_dec 
** is permitted because of the following sub-derivation:

dec list(dec) // lookahead token appears because list(dec) can begin with TYPE
dec_ty_fun // lookahead token is inherited
nonempty_list(loc(ty_dec)) // lookahead token is inherited
ty_dec . 

** In state 143, looking ahead at TYPE, shifting is permitted
** because of the following sub-derivation:

dec list(dec) 
dec_ty_fun 
nonempty_list(loc(ty_dec)) 
ty_dec nonempty_list(loc(ty_dec)) 
       ty_dec 
       . TYPE symbol EQ ty 

[vyorkin]

Affects #2