Improve diff highlight (#3390)

- Try to reduce memory allocations
- Add possibility to disable diff highlight (can improve performance for large diffs)
- Tweaking with cost for prettier (cleaner) diffs
- Do not calculate diff when the number of removed lines in a block is not equal to the number of added lines (this usually resulted in ugly diffs)

1 files changed, 1 insertions, 0 deletions

diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index 0de1963c5c..6581efe4f0 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -191,6 +191,7 @@ var (
 
 	// Git settings
 	Git struct {
+		DisableDiffHighlight     bool
 		MaxGitDiffLines          int
 		MaxGitDiffLineCharacters int
 		MaxGitDiffFiles          int