Implement ubrk.h

[bdragon]

Adds bindings for ubrk.h

Closes #166

API

ICU4C API	Rust API
ubrk_close	impl Drop
ubrk_next	impl Iterator
ubrk_countAvailable	count_available_locales
ubrk_getAvailable	get_available_locale_at
ubrk_open	try_new, try_new_ustring
ubrk_openRules	try_new_rules, try_new_rules_ustring
ubrk_openBinaryRules	try_new_binary_rules, try_new_binary_rules_ustring
ubrk_getBinaryRules	get_binary_rules
ubrk_safeClone	safe_clone
ubrk_setText	set_text, set_text_ustring
ubrk_setUText	Not implemented.1
ubrk_refreshUText	Not implemented.1
ubrk_previous	previous
ubrk_current	current
ubrk_preceding	preceding
ubrk_following	following
ubrk_first	first
ubrk_last	last_boundary2
ubrk_isBoundary	is_boundary
ubrk_getLocaleByType	get_locale_by_type
ubrk_getRuleStatus	get_rule_status
ubrk_getRuleStatusVec	get_rule_status_vec

---

¹ In light of #6 and the existing UText implementation, it made sense to leave these out for now.

² The Rust Iterator trait already provides a last() method, so I had to name this differently in order to avoid a conflict.

[bdragon]

Minor thing: I noticed that when the simple_drop_impl! macro is used, make cov does not treat the referenced ICU *_close API as implemented in the coverage report, so I added an Implements ... doc comment above the macro. This caused make cov to consider the ICU API implemented, at the expense of a warning:

95 | /// Implements `ubrk_close`.
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ rustdoc does not generate documentation for macro invocations

[filmil]

Minor thing: I noticed that when the simple_drop_impl! macro is used, make cov does not treat the referenced ICU *_close API as implemented in the coverage report, so I added an Implements ... doc comment above the macro. This caused make cov to consider the ICU API implemented, at the expense of a warning:

95 | /// Implements `ubrk_close`.
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ rustdoc does not generate documentation for macro invocations

You will note that elsewhere I use // Implements ... instead of ... where the macro is invoked to work around this issue.
Since the macro expansion itself contains the three-slashed version of the same text, the end result comes out OK in both rustdoc and compilation - without warnings.

[bdragon]

Thanks. Updated in d1876d5.

[filmil]

I'm now looking at this PR.

[bdragon]

I found a couple of broken links in the doc comments. Fixed in 1932074.

[bdragon]

@filmil I appreciate the review. I believe I have addressed your feedback if you don't mind taking another look.

[filmil]

Thank you for making the changes, I'll take a look as soon as able, but at the moment it seems will need to happen tomorrow.

[filmil]

Re-reviewing now.

[filmil]

Thank you for your patience for the review. This is now approved.