This follows up 0a7e01ae.

Specifically, nlr.h does.

TODO: Rename methods.

This is ugly, just as expected.

Biggest part of this support is refactoring mp_obj_class_lookup() to return
standard "bound member" pair (mp_obj_t[2]). Actual support of inherited
native methods is 3 lines then. Some inherited features may be not supported
yet (e.g. native class methods, native properties, etc., etc.). There may
be opportunities for further optimization too.

This implements checking of base types, allocation and basic initialization,
and optimized support for special method lookups. Other features are not yet
supported.

This is a one-liner fix.  It gets the class-super.py test passing, but
is probably not a complete fix.

Also make consistent use of MP_OBJ_NOT_SUPPORTED and MP_OBJ_NULL.
This helps a lot in debugging and understanding of function API.

mp_obj_t->subscr now does load/store/delete.

Enabled by MICROPY_ENABLE_PROPERTY.

This makes the runtime and object APIs more consistent.  mp_store_subscr
functionality now moved into objects (ie list and dict store_item).

At this point, all opcodes are now implemented!

Some del opcodes have been combined with store opcodes, with the value
to store being MP_OBJ_NULL.

This makes isinstance(X, object) and issubclass(X, object) true for all
X.

This does not affect code size or performance when debugging turned off.

To address issue #420.

It's not completely satisfactory, because a failed call to __getattr__
should not raise an exception.

__setattr__ could be implemented, but it would slow down all stores to a
user created object.  Need to implement some caching system.

Because it's runtime reflection feature, not required for many apps.
Rant time:
Python could really use better str() vs repr() distinction, for example,
repr(type) could be "<class 'foo'>" (as it is now), and str(type) just
"foo". But alas, getting straight name requires adhoc attribute.

It's virtual because it's not shown in dir(...). (That's also how CPython
has it).

Pretty much everyone needs to include map.h, since it's such an integral
part of the Micro Python object implementation.  Thus, the definitions
are now in obj.h instead.  map.h is removed.

Mostly just a global search and replace.  Except rt_is_true which
becomes mp_obj_is_true.

Still would like to tidy up some of the names, but this will do for now.

Addresses issue #388.

Originally, .methods was used for methods in a ROM class, and
locals_dict for methods in a user-created class.  That distinction is
unnecessary, and we can use locals_dict for ROM classes now that we have
ROMable maps.

This removes an entry in the bloated mp_obj_type_t struct, saving a word
for each ROM object and each RAM object.  ROM objects that have a
methods table (now a locals_dict) need an extra word in total (removed
the methods pointer (1 word), no longer need the sentinel (2 words), but
now need an mp_obj_dict_t wrapper (4 words)).  But RAM objects save a
word because they never used the methods entry.

Overall the ROM usage is down by a few hundred bytes, and RAM usage is
down 1 word per user-defined type/class.

There is less code (no need to check 2 tables), and now consistent with
the way ROM modules have their tables initialised.

Efficiency is very close to equivaluent.

Addresses issue #377.

Remove unnecessary includes. Add includes that improve portability.

I.e. as replacement of MP_OBJ_IS_TYPE(), which takes into account subclassing.

Each built-in exception is now a type, with base type BaseException.
C exceptions are created by passing a pointer to the exception type to
make an instance of.  When raising an exception from the VM, an
instance is created automatically if an exception type is raised (as
opposed to an exception instance).

Exception matching (RT_BINARY_OP_EXCEPTION_MATCH) is now proper.

Handling of parse error changed to match new exceptions.

mp_const_type renamed to mp_type_type for consistency.

Ultimately all static strings should be qstr.  This entry in the type
structure is only used for printing error messages (to tell the type of
the bad argument), and printing objects that don't supply a .print method.

Some tools do not support local/static symbols (one example is GNU ld map file).
Exposing all functions will allow to do detailed size comparisons, etc.

Also, added bunch of statics where they were missing, and replaced few identity
functions with global mp_identity().