Add ability to import modules with dashes or spaces

Any module with underscores in it will now attempt to look for 3 files,
first the original, then with dashes, then with spaces, ie:
import addressbook_v_2_capnp
will search for 'addressbook_v_2.capnp', 'addressbook-v-2.capnp', and
'addressbook v 2.capnp'.

capnp/lib/capnp.pyx

@@ -3116,6 +3116,12 @@ class _Importer:
 
         module_name = module_name[:-len('_capnp')]
         capnp_module_name = module_name + self.extension
+        has_underscores = False
+
+        if '_' in capnp_module_name:
+            capnp_module_name_dashes = capnp_module_name.replace('_', '-')
+            capnp_module_name_spaces = capnp_module_name.replace('_', ' ')
+            has_underscores = True
 
         if package_path:
             paths = package_path
@@ -3134,8 +3140,14 @@ class _Importer:
                 path = _os.getcwd()
             elif not is_abs(path):
                 path = abspath(path)
+
             if is_file(path+sep+capnp_module_name):
                 return _Loader(fullname, join_path(path, capnp_module_name), self.additional_paths)
+            if has_underscores:
+                if is_file(path+sep+capnp_module_name_dashes):
+                    return _Loader(fullname, join_path(path, capnp_module_name_dashes), self.additional_paths)
+                if is_file(path+sep+capnp_module_name_spaces):
+                    return _Loader(fullname, join_path(path, capnp_module_name_spaces), self.additional_paths)
 
 _importer = None
 

test/addressbook with spaces.capnp

@@ -0,0 +1,39 @@
+@0xc39aee9191aedcf3;
+
+const qux :UInt32 = 123;
+
+struct Person {
+  id @0 :UInt32;
+  name @1 :Text;
+  email @2 :Text;
+  phones @3 :List(PhoneNumber);
+
+  struct PhoneNumber {
+    number @0 :Text;
+    type @1 :Type;
+
+    enum Type {
+      mobile @0;
+      home @1;
+      work @2;
+    }
+  }
+
+  employment :union {
+    unemployed @4 :Void;
+    employer @5 :Employer;
+    school @6 :Text;
+    selfEmployed @7 :Void;
+    # We assume that a person is only one of these.
+  }
+}
+
+struct Employer {
+  name @0 :Text;
+  boss @1 :Person;
+}
+
+struct AddressBook {
+  people @0 :List(Person);
+}
+

test/addressbook-with-dashes.capnp

@@ -0,0 +1,39 @@
+@0xd33206731939e03b;
+
+const qux :UInt32 = 123;
+
+struct Person {
+  id @0 :UInt32;
+  name @1 :Text;
+  email @2 :Text;
+  phones @3 :List(PhoneNumber);
+
+  struct PhoneNumber {
+    number @0 :Text;
+    type @1 :Type;
+
+    enum Type {
+      mobile @0;
+      home @1;
+      work @2;
+    }
+  }
+
+  employment :union {
+    unemployed @4 :Void;
+    employer @5 :Employer;
+    school @6 :Text;
+    selfEmployed @7 :Void;
+    # We assume that a person is only one of these.
+  }
+}
+
+struct Employer {
+  name @0 :Text;
+  boss @1 :Person;
+}
+
+struct AddressBook {
+  people @0 :List(Person);
+}
+

test/test_load.py

@@ -58,6 +58,12 @@ def test_failed_import():
 def test_defualt_import_hook():
     import addressbook_capnp
 
+def test_dash_import():
+    import addressbook_with_dashes_capnp
+
+def test_spaces_import():
+    import addressbook_with_spaces_capnp
+
 def test_add_import_hook():
     capnp.add_import_hook([this_dir])