[gsac] Add position argument to string code lift constructor

Ignore-this: 51c7218d6eae1c379ebbd4cff214d537

darcs-hash:20130930031808-2809a-ccf1771988ee68b71eb0f563b92ff8ecd93d9582
[gsac] Parse tree for .tylift type expressions

Ignore-this: be311102c4da63c84e5dbdd8f963076a

darcs-hash:20130930040519-2809a-ff3cb9e19286d86b02134b847181fdd62ff628c7
[gsac] .tysum parse tree

Ignore-this: 6de9572a2c1a5c0a6f2cb47195dc8779

darcs-hash:20131006020608-2809a-e08b844d5dd4ec495bac977a77d641ccbc155011
[gsac] gsdl.cgs.gstype.constr.t

Ignore-this: 3b4496c3d4ecde479180512452e94776

darcs-hash:20131006025650-2809a-49cff727375d44814f7839ac11187d3aba83a007
[gsac] gsdl.cgs.gstype.sum

Ignore-this: 5be1678b29985e9c3fba83c0968acb6c

darcs-hash:20131006040909-2809a-d27d95a6e3f3a58db05771d0acf7206eec795ca0
[gsac] gsdl.cgs.symbol.compare/abstyvar/tyvar

Ignore-this: c95e2d80d1619946ba1e6aaa796a8a62

darcs-hash:20131006122625-2809a-25d3af5de0ef04a42d7b9d16065b7aedbc0b063a
[gsac] Fill out ordered.set.union

Ignore-this: f95395587f3bc96e18766dfea6a44eba

darcs-hash:20131006123733-2809a-2f73f95581e5abce843b0f65663d3f871f55c3e1