The Complex class needs `mrb_float` so that it does not work with
`MRB_WITHOUT_FLOAT` anyway.

Now `rand` can be used with `MRB_WITHOUT_FLOAT`; ref #4576

Normal `TYPED_FIXABLE(f,mrb_float)` does not work on 64bit int from
casting problems. The new approach works well, but assumes two's
complement and IEEE-754 floating point numbers.

Refine `String#chr` test and separate `Fixnum#chr` test

Use stack memory for small name of attr accessors

Fix `String#*` test with `MRB_WITHOUT_FLOAT`

Fix `String#[]` test

Fix `(fixnum_value ... float_value).min` with `mruby-range-ext`

Revert #4300

Allow `mruby-range-ext` to work with `MRB_WITHOUT_FLOAT`; ref 2add8641

Originally, it was not necessary to change. I made mistake.

Before this patch:

  $ bin/mruby -e 'p (2...4.0).min'  #=> TypeError

After this patch (same as CRuby and without `mruby-range-ext`):

  $ bin/mruby -e 'p (2...4.0).min'  #=> 2

Functions that are called infrequently need not to be inline.

Let inspect recursion do the right thing

Copy receiver's `MRB_STR_ASCII` flag in some methods of `String`

Error needed/conflicts configuration

Unify type of line number to `uint16_t`

Keep `MRB_STR_ASCII` flag in some methods of `String`

Improve `utf8len()` performance with UTF-8

 Fix pack/unpack for base64; ref #4556

For example, `"".unpack("")` evaluates to `[]`.

The pack/unpack "m" directive should be treated as a length rather than
an element count.