Add whitespace handling to PR-comparsion (#4683)

* Add whitespace handling to PR-comparsion

In a PR we have to keep an eye on a lot of different things. But sometimes the
bare code is the key-thing we want to care about and just don't want to care
about fixed indention on some places. Especially if we follow the pathfinder
rule we face a lot of these situations because these changes don't break the
code in many languages but improve the readability a lot.

So this change introduce a fine graned button to adjust the way how the
reviewer want to see whitespace-changes within the code.

The possibilities reflect the possibilities from git itself except of the
`--ignore-blank-lines` flag because that one is also handled by `-b` and is
really rare.

Signed-off-by: Felix Nehrke <felix@nehrke.info>

routers/repo/pull.go

@@ -390,6 +390,12 @@ func ViewPullFiles(ctx *context.Context) {
 	}
 	pull := issue.PullRequest
 
+	whitespaceFlags := map[string]string{
+		"ignore-all":    "-w",
+		"ignore-change": "-b",
+		"ignore-eol":    "--ignore-space-at-eol",
+		"":              ""}
+
 	var (
 		diffRepoPath  string
 		startCommitID string
@@ -455,11 +461,12 @@ func ViewPullFiles(ctx *context.Context) {
 		ctx.Data["Reponame"] = pull.HeadRepo.Name
 	}
 
-	diff, err := models.GetDiffRange(diffRepoPath,
+	diff, err := models.GetDiffRangeWithWhitespaceBehavior(diffRepoPath,
 		startCommitID, endCommitID, setting.Git.MaxGitDiffLines,
-		setting.Git.MaxGitDiffLineCharacters, setting.Git.MaxGitDiffFiles)
+		setting.Git.MaxGitDiffLineCharacters, setting.Git.MaxGitDiffFiles,
+		whitespaceFlags[ctx.Data["WhitespaceBehavior"].(string)])
 	if err != nil {
-		ctx.ServerError("GetDiffRange", err)
+		ctx.ServerError("GetDiffRangeWithWhitespaceBehavior", err)
 		return
 	}