Make Basis look column-major while retaining a row-major representation

Per https://github.com/godotengine/godot/issues/14553:
Godot stores Basis in row-major layout for more change for efficiently
taking advantage of SIMD instructions, but in scripts Basis looks like and
is accessible in a column-major format.

This change modifies the C++ binding so that from the script's perspective
Basis does look like if it was column-major while retaining a row-major
in-memory representation. This is achieved using a set of helper template
classes which allow accessing individual columns whose components are
non-continues in memory as if it was a Vector3 type. This ensures script
interface compatibility without needing to transpose the Basis every time
it is passed over the script-engine boundary.

Also made most of the Vector2 and Vector3 class interfaces inlined in the
process for increased performance.

While unrelated (but didn't want to file a separate PR for it), this change
adds the necessary flags to have debug symbol information under MSVC.

Fixes #241.

SConstruct

@@ -98,7 +98,7 @@ elif env['platform'] == 'windows':
         # MSVC
         env.Append(LINKFLAGS=['/WX'])
         if env['target'] == 'debug':
-            env.Append(CCFLAGS=['/EHsc', '/D_DEBUG', '/MDd'])
+            env.Append(CCFLAGS=['/Z7', '/Od', '/EHsc', '/D_DEBUG', '/MDd'])
         elif env['target'] == 'release':
             env.Append(CCFLAGS=['/O2', '/EHsc', '/DNDEBUG', '/MD'])
     else: