ChangeScreen2: Add 'Diff against' to select base revision

Add dropdown on the Files header section to select
reference version for loading the revision.

Change-Id: I5c40a52b0018fea7e11ac67696ee6fb7b4674349
(cherry picked from commit 2d2a3c405e5472f27b96484b068f51c34ee5e6cb)
ChangeScreen2: Make diff against revision persistent

2d2a3c405e5472f27b96484b068f51c34ee5e6cb added diff against to the change
screen2. However base revision is lost when side by side view is closed.

This change fixes that.

Conflicts:
	gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ChangeScreen2.java

Change-Id: I7f74760fde96469a60556f657923a3936d6516c7
ChangeScreen2: Add key binding for Expand All/Collapse All buttons

eb924ff74a90bbeb37cd3856dae4e9325598656b inroduced one of the most wanted
features, that the whole community has been waiting for years. Let's add
key bindings for that too.

Change-Id: I9b159a9a877cf95edd1628329a9448de3a59fe21
(cherry picked from commit 79f675a5a52c0f7ec6943cfdb6760462d615a432)
ChangeScreen2: Update the documentation with recently made changes

Change-Id: I939710ed7c8c96c51dabb0c013093c9c0fda7bd6
(cherry picked from commit 3e0299b5ad84914f9350f150f10f5e6cb4f3ada3)
Merge changes I7f74760f,I5c40a52b into stable-2.8

* changes:
  ChangeScreen2: Make diff against revision persistent
  ChangeScreen2: Add 'Diff against' to select base revision
Merge "ChangeScreen2: Update the documentation with recently made changes" into stable-2.8
Fix build errors

Commit e786675 cherry-picked from master caused the build to fail
because of a missing import and missing message string definition.

Add the missing import and message definition.

Change-Id: I2639816d86e232c67421c91b594281b9b0a9bb8f
Merge branch 'stable-2.8'

* stable-2.8:
  Fix build errors
  ChangeScreen2: Update the documentation with recently made changes
  ChangeScreen2: Make diff against revision persistent
  ChangeScreen2: Add 'Diff against' to select base revision

Merged with `-s ours` to prevent conflicts.

Change-Id: I5dcdf67e5eb18f0a8da8b4deca001c9103bda549
Merge "ChangeScreen2: Add key binding for Expand All/Collapse All buttons" into stable-2.8
Document that `reindex` must be run after enabling the secondary index

If the index is enabled, but not built before Gerrit is started, Gerrit
fails to start with IllegalStateException.

Update the documentation to mention that the `reindex` program must be
run after enabling the index.

Change-Id: I6e5fb35c408cf315c222577b23e14656b9e76810
Merge branch 'stable-2.8'

* stable-2.8:
  Document that `reindex` must be run after enabling the secondary index
  ChangeScreen2: Add key binding for Expand All/Collapse All buttons

Change-Id: I689dea3572b22836829d4b3d72b9f0b8d0d2958c
Trim ProjectApiImpl

Do not need inject CreateBranch.Factory, delete it.
Rename ProjectResource parameter from 'change' to 'project'.

Change-Id: I039d07fa4499bdc6acce96437cf884be6431a049
Merge "Trim ProjectApiImpl"