Retire vendored cacycle_diff.js for a diff-lcs-based diff view

Revisions#diff now computes an inline or side-by-side word diff
server-side (Page#diff_against, lib/html_word_diff.rb) instead of
shipping raw/escaped content to the browser for a 2008-era vendored
JS differ to mangle. View mode is picked via a `view` param, settable
either on the diff page itself or directly from the revisions#index
sticky bar next to "Diff revisions".

Also fixes a pre-existing bug in RevisionsController#diff's single-
revision branch, which set params[:start]/params[:end] instead of
params[:start_revision]/params[:end_revision].

1 files changed, 3 insertions, 0 deletions

diff --git a/Gemfile.lock b/Gemfile.lock
index 02c71ff..e6f5fa0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -108,6 +108,7 @@ GEM
     connection_pool (3.0.2)
     crass (1.0.7)
     date (3.5.1)
+    diff-lcs (2.0.0)
     drb (2.2.3)
     erb (6.0.4)
     erubi (1.13.1)
@@ -330,6 +331,7 @@ DEPENDENCIES
   chaos_calendar!
   coffee-rails (~> 4.0)
   concurrent-ruby (~> 1.3)
+  diff-lcs
   exception_notification (~> 4.5)
   globalize (~> 7.0)
   jquery-rails
@@ -377,6 +379,7 @@ CHECKSUMS
   connection_pool (3.0.2) sha256=33fff5ba71a12d2aa26cb72b1db8bba2a1a01823559fb01d29eb74c286e62e0a
   crass (1.0.7) sha256=94868719948664c89ddcaf0a37c65048413dfcb1c869470a5f7a7ceb5390b295
   date (3.5.1) sha256=750d06384d7b9c15d562c76291407d89e368dda4d4fff957eb94962d325a0dc0
+  diff-lcs (2.0.0) sha256=708a5d52ec2945b50f8f53a181174aa1ef2c496edf81c05957fe956dabb363d5
   drb (2.2.3) sha256=0b00d6fdb50995fe4a45dea13663493c841112e4068656854646f418fda13373
   erb (6.0.4) sha256=38e3803694be357fe2bfe312487c74beaf9fb4e5beb3e22498952fe1645b95d9
   erubi (1.13.1) sha256=a082103b0885dbc5ecf1172fede897f9ebdb745a4b97a5e8dc63953db1ee4ad9