CSharp test-suite support on windows

- Add pathconvert tool to convert to a windows path for input files for
  C# compiler
- Simplify vcfilter

Tools/convertpath

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+# Unix to Windows relative path conversion in a script.
+# Useful for avoiding backslash quoting difficulties in Makefiles.
+# Acts as a much dumbed down 'cygpath -w' tool.
+
+usage()
+{
+  cat <<EOF
+Usage: $0 [-w|-u|-h] [path]...
+
+Convert Windows and Unix paths (intended for simple relative paths only)
+
+  -w  Convert backslashes to forward slashes in the paths
+  -u  Convert forward slashes to backslashes in the paths
+EOF
+}
+
+option="$1"
+case "$option" in
+  -w) shift; echo $@ | sed -e 's,/,\\,g' ;;
+  -u) shift; echo $@ | sed -e 's,\\,/,g' ;;
+  -h) shift; usage; ;;
+  *) usage; exit 1 ;;
+esac
+
+exit 0

Tools/vcfilter

@@ -2,9 +2,9 @@
 
 # This is a simple utility for Cygwin/Mingw which is useful when running the SWIG
 # test-suite through Visual Studio. If the output from the test-suite is piped
-# through this utility, it will filter the junk that the compiler generates.
+# through this utility, it will filter the junk that the compiler outputs to stdout.
 # Typical usage: make check | vcfilter
 
 # dos2unix needed for ^ and $ to work.
-2>&1 dos2unix | grep -v "\.cxx$" | grep -v "\.c$" | grep -v "^   Creating library" | grep -v "^Generating Code"
+2>&1 dos2unix | grep -v -e "\.cxx$" -e "\.c$" -e "^   Creating library" -e "^Generating Code"