Add support for namespaces.

For details of the new feature, see
https://github.com/luarocks/luarocks/wiki/Namespaces

This ended up being a huge commit because of some major refactoring
motivated by the new feature:

* new modules for some object types:
  * `luarocks.queries` - all functions that look for rocks in local or
    remote repositories now use objects constructed by this module:
    query objects contain the name, namespace and query constraints.
    Dependencies in a rockspec are also stored as query objects.
  * `luarocks.results` - all individual results produces from queries
    are returned in this format: result objects contain the name,
    namespace, version, arch and repo.
* the `results` object was renamed to `result_tree`, to better
  reflect that it is not an array of `result` objects.
* `luarocks.vers` was removed, its functionality was moved to better locations.

Specifically on namespaces:

* Commands that take a rock `name` can now take `namespace/name`
  (and alternately `--flags=namespace` so that URLs can be
  also installed with a nominal namespace).
* Rocks installed from a namespace now create a `rock_namespace`
  file alongside `rock_manifest`, which is used when matching
  namespaced dependencies against locally-installed rocks.
* Using namespaced dependencies in a rockspec, requires
  `rockspec_format = "3.0"`.
* Tests under the `#namespaces` hashtag, all using a local repository.

4 files changed, 80 insertions, 0 deletions

diff --git a/spec/fixtures/a_repo/manifest b/spec/fixtures/a_repo/manifest
index ea198207..141dafb5 100644
--- a/spec/fixtures/a_repo/manifest
+++ b/spec/fixtures/a_repo/manifest
@@ -10,5 +10,25 @@ repository = {
             arch = "rockspec"
          }
       }
+   },
+   has_another_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
+   },
+   has_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
    }
 }
diff --git a/spec/fixtures/a_repo/manifest-5.1 b/spec/fixtures/a_repo/manifest-5.1
index ea198207..141dafb5 100644
--- a/spec/fixtures/a_repo/manifest-5.1
+++ b/spec/fixtures/a_repo/manifest-5.1
@@ -10,5 +10,25 @@ repository = {
             arch = "rockspec"
          }
       }
+   },
+   has_another_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
+   },
+   has_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
    }
 }
diff --git a/spec/fixtures/a_repo/manifest-5.2 b/spec/fixtures/a_repo/manifest-5.2
index ea198207..141dafb5 100644
--- a/spec/fixtures/a_repo/manifest-5.2
+++ b/spec/fixtures/a_repo/manifest-5.2
@@ -10,5 +10,25 @@ repository = {
             arch = "rockspec"
          }
       }
+   },
+   has_another_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
+   },
+   has_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
    }
 }
diff --git a/spec/fixtures/a_repo/manifest-5.3 b/spec/fixtures/a_repo/manifest-5.3
index ea198207..141dafb5 100644
--- a/spec/fixtures/a_repo/manifest-5.3
+++ b/spec/fixtures/a_repo/manifest-5.3
@@ -10,5 +10,25 @@ repository = {
             arch = "rockspec"
          }
       }
+   },
+   has_another_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
+   },
+   has_namespaced_dep = {
+      ["1.0-1"] = {
+         {
+            arch = "rockspec"
+         },
+         {
+            arch = "src"
+         }
+      }
    }
 }