Improve path normalization for approvalTests.py

This fixes 3 problems:

* Relative paths on Windows are now supported
* Out-of-tree (paths starting with ../) builds are now supported
* Path separator normalization no longer affects non-path components of input (problem with Compact reporter)


Fixes #1379 
Fixes #1222 
Fixes #1200 
Fixes #1194

scripts/approvalTests.py

@@ -18,7 +18,7 @@ if os.name == 'nt':
 
 rootPath = os.path.join(catchPath, 'projects/SelfTest/Baselines')
 
-
+langFilenameParser = re.compile(r'(.+\.[ch]pp)')
 filelocParser = re.compile(r'''
     .*/
     (.+\.[ch]pp)  # filename
@@ -91,12 +91,24 @@ def diffFiles(fileA, fileB):
     return [line for line in diff if line[0] in ('+', '-')]
 
 
-def filterLine(line, isCompact):
+def normalizeFilepath(line):
     if catchPath in line:
         # make paths relative to Catch root
         line = line.replace(catchPath + os.sep, '')
+
+    m = langFilenameParser.match(line)
+    if m:
+        filepath = m.group(0)
         # go from \ in windows paths to /
-        line = line.replace('\\', '/')
+        filepath = filepath.replace('\\', '/')
+        # remove start of relative path
+        filepath = filepath.replace('../', '')
+        line = line[:m.start()] + filepath + line[m.end():]
+
+    return line
+
+def filterLine(line, isCompact):
+    line = normalizeFilepath(line)
 
     # strip source line numbers
     m = filelocParser.match(line)