[fidl] Minor corrections.

Test: Doc changes.

Change-Id: If6b3ddb6539641560cce4eb20ea5c154436524ac

[fidl] Update docs now that |status| is not reserved

Test: Just changes docs
Change-Id: Id163f430c0faa3d68564dfc9f3862e298cd6806e

[fidl] Add using type aliasing

This CL implements most of FTP-002. You can use use "zx.time" and
"zx.duration". The situation for status is complicated by the fact that
status is currently a keywork in FIDL. You can use the new definition
as "zx.@status". Once we migrate all clients off the "status" keyword
and onto "zx.@status", we can complete FTP-002 by removing the keyword
from the compiler and migrating all clients from "zx.@status" to
"zx.status".

FIDL-253 #comment

Test: spaceship.fidl
Change-Id: I93f508dc95ecc56a3cdbd3fc1c40346d358aeefe

[fidl] Disallow empty enums

Change-Id: I8db20696ec537e895f8fb2ad17c67b2a735f5a03

[fidl] Parse (but do not yet use) multipart library names

Change-Id: Ic3fe6a34e8e2fc44a315b3402669f4fbe6893a8c

[fidl] Remove nested declarations

FIDL-188 #done

Change-Id: I8fbcce98ed8fa81f4c91a99f062b8e129c4e5124

[fidl] Compile and typecheck const declarations

This patch generates dependency edges for const declaration ordering,
and (partially) checks that the type and value of the declaration line
up.

TO-702

Change-Id: I32b4c1fbef6d2e054b0a6cd1008c5937472f676a

[fidl][doc] Describe comments in the grammar

Change-Id: I55cd04fefb047221119df44fa52e1d9bdfcb54d9

[fidl] Library names don't have scope

Change-Id: I24dbc5db404b2f058963858ffe521d0d6d1cd770

[fidl] Add support for attributes on declarations

We'll use this for the [ServiceName] attribute on interfaces.

Change-Id: I1371e6363fd1dc3566f18c8721de0ed3e6203634

[fidl][zx] Sync object types between FIDL and zx

Several of the object types referenced by the FIDL spec no longer exist.
Also, add two missing object types to libzx.

Change-Id: I18a00110912b99fd734a59e5a390de94ef433799

[fidl] Disallow empty unions

An empty union has no valid wire format representations. A void type
makes little sense in an IPC protocol.

Change-Id: I27b55520f0763dc3cfab6ed2e61adf4a8ec96115

[fidl] Tweak the syntax of event methods

Several people have found this syntax's symmetry with the other method
styles considerably more intuitive than the event keyword.

Change-Id: I75c4d8e88db01cb856d5025dd3eb2e29f50d6eaa

[fidl][docs] Update docs to match the FIDL2 examples.

Change-Id: I09578c0728c12fcfeb65081390fb91862ae20d5e

[fidl][semicolons] Parse semicolons after declarations

Per the originally drafted FIDL2 spec, semicolons follow all
declarations (including library and using declarations). Enough people
have seen that document and been acclimated to it that it seems best
to conform to that expectation.

Change-Id: If2b9c75f77d564e735e26eb5b50bdf91ce940855

[fidl] Parse 'status' as a builtin type

Eventually we may want to evaluate a more general mechanism for
aliasing types, and provide some builtin-aliases. But zx_status_t
stands out as deserving of special syntax for now.

Change-Id: I5fe51d111fe27a42a55a43dd487ffa57a9c1d325

[fidl] Parse interface extensions

Change-Id: I51ca2255713ec0d8f21eee0db76121ea7c3e258c

[fidl] Parse event ordinal kinds

Change-Id: Iadff8cd016407ccb362bef89923bb8c65e0a1d37

[docs][fidl] Add fidl grammar

Change-Id: Iec52205571e5052f429a34ff38379d46e82afad0