opam: switch to 2.0 format

opam

@@ -1,10 +1,11 @@
-opam-version: "1.2"
+opam-version: "2.0"
 maintainer: "[email protected]"
 homepage: "https://github.com/ygrek/ocaml-extlib"
 dev-repo: "git://github.com/ygrek/ocaml-extlib.git"
 bug-reports: "https://github.com/ygrek/ocaml-extlib/issues"
 doc: ["http://ygrek.org.ua/p/extlib/doc/"]
 license: "LGPL-2.1 with OCaml linking exception"
+synopsis: "A complete yet small extension for OCaml standard library"
 authors: [
   "Nicolas Cannasse"
   "Brian Hurt"
@@ -21,15 +22,17 @@ authors: [
 ]
 build: [
   [make "minimal=1" "build"]
+  [make "test"] {with-test}
+  [make "doc"] {with-doc}
 ]
 install: [ [make "minimal=1" "install"] ]
-build-doc: [ [make "doc"] ]
-build-test: [ [make "test"] ]
 remove: [
   ["ocamlfind" "remove" "extlib"]
 ]
 depends: [
+  "ocaml"
   "ocamlfind" {build}
   "cppo" {build}
   "base-bytes" {build}
 ]
+flags: light-uninstall