Remove no longer used arguments from the functions.

`a::B = c` should evaluate `a` then `c`. It used to be `c` then `a`. The
`OP_SETMCNST` instruction operands are designed for older order in mind.
Should we changed the operand order?

Fix tree of mruby-bin-example

But `mktime(3)` for the date returns `-1` which happen to be the
error value.

It was caused by #5628.

Toplevel includes the top of the method/class/module definitions.

Fixes file header in src/{cdump,dump}.c [ci skip]

The file headers were pointing to each other's files.

Fixing keyword arguments with `super`

Allows handling of unaligned cptrs for `MRB_NAN_BOXING`

This reverts commit d3b7601a.

It seems to be preferable to be able to handle pointers of type `char` as well.
For this purpose, `mrb_nanbox_tt_inline` has been reorganized.

- `MRB_NANBOX_TT_POINTER` has been split into `MRB_NANBOX_TT_OBJECT` and `MRB_NANBOX_TT_CPTR`
- `MRB_NANBOX_TT_SYMBOL` has been merged into `MRB_NANBOX_TT_MISC`

fix #5627

Improves presym scanning

Assert that `MRB_METHOD_CACHE_SIZE` is a power of 2

Assign after `mrb_irep_incref()` in `mrb_proc_new()`

Call functions directly from `mrb_ensure_float_type()`

Adjusting the stack for after it enters the virtual machine

ref. 28ccc664

The `mrb_static_assert_powerof2()` macro has been introduced for this purpose.

The main purpose is to increase the chances of finding presym and to prevent errors due to C++11 lambda expressions.

- The argument to receive the class may be written, for example, `mrb_class_get()`.
- The argument that receives the implementation function of the method may be a C++ lambda expression.
  In this case, if multiple variable declarations are separated by colons, the preprocessor will recognize them as argument delimiters and report an error.
  This patch prevents it from happening.

  ```c++
  // When preprocessing...
  func([] { int x, y, z; })
    // ^^^^^^^^^^          1st argument?
    //             ^       2nd argument?
    //                ^^^^ 3rd argument?
  ```

It may cause broken reference count numbers.

ref. commit 7f40b645

Currently, the build configurations `MRB_USE_COMPLEX` and `MRB_USE_RATIONAL` are not listed in the documentation.
In other words, they are hidden settings.
They are defined in `mrbgems/mruby-{complex,rational}/mrbgem.rake`.
So this patch assumes that it is safe to refer to these functions in core-gems directly from core functions.

However, applications that link with `libmruby_core.a` will have compatibility issues.
In fact, `mrbgems/mruby-bin-mrbc` links with `libmruby_core.a`, so I had to prepare a dummy function.