Files can be set not to use 'ignore-all' by default.

Summary:
Python people don't seem to like the 'ignore-all' as default. Provide a way
to configure which file types should not use 'ignore-all'.

Test Plan:
Tested that it worked with bunch of Python of files and non-python
files. Cache was disabled during the test.

Reviewed By: jungejason
Reviewers: epriestley, jungejason
Commenters: epriestley
CC: aran, jungejason, epriestley
Differential Revision: 713

src/applications/differential/parser/changeset/DifferentialChangesetParser.php

@@ -767,6 +767,10 @@ class DifferentialChangesetParser {
 
         $ignore_all = ($this->whitespaceMode == self::WHITESPACE_IGNORE_ALL);
 
+        if ($ignore_all && $changeset->getWhitespaceMatters()) {
+          $ignore_all = false;
+        }
+
         // The "ignore all whitespace" algorithm depends on rediffing the
         // files, and we currently need complete representations of both
         // files to do anything reasonable. If we only have parts of the files,