VPP-57 Add Doxygen to VPP

- Configures Doxygen.
- Adds a source filter to do magic on our use of the preprocessor to do
  constructor stuff to make Doxygen grok it better.
- Adds a convenience helper to the root Makefile.
- Adds a README.md to the root directory (and which Doxygem uses as its
  "mainpage".
- Add several other documentative files.
- Currently using SVG for call graphs, though this may have a
  load-time performance impact in browsers.

Change-Id: I25fc6fb5bf634319dcb36a7f0e32031921c125ac
Signed-off-by: Chris Luke <chrisy@flirble.org>

2 files changed, 47 insertions, 0 deletions

diff --git a/doxygen/assets/doxy-vpp.css b/doxygen/assets/doxy-vpp.css
new file mode 100644
index 00000000000..3b74eb6f66b
--- /dev/null
+++ b/doxygen/assets/doxy-vpp.css
@@ -0,0 +1,47 @@
+/* VPP CSS overrides */
+
+body, table, div, p, dl {
+	font: initial;
+	font-family: Lucida Grande, Verdana, Geneva, Arial, sans-serif;
+	font-size: small;
+}
+
+code, tt {
+	font: initial;
+	font-family: Consolas, Courier, monospace;
+	font-size: small;
+}
+
+pre {
+	font-size: 105%;
+}
+
+
+.title {
+	font: initial;
+	font-family: Lucida Grande, Verdana, Geneva, Arial, sans-serif;
+	font-size: 150%;
+	font-weight: bold;
+}
+
+
+.mdescLeft, .mdescRight,
+.memItemLeft, .memItemRight,
+.memTemplItemLeft, .memTemplItemRight, .memTemplParams {
+	font-family: Consolas, Courier, monospace;
+}
+
+.memname {
+	font-family: Consolas, Courier, monospace;
+	font-weight: bold;
+	font-size: 105%;
+}
+
+.paramname {
+	font-family: Consolas, Courier, monospace;
+	font-weight: bold;
+}
+
+a.el {
+	font-family: Consolas, Courier, monospace;
+}
diff --git a/doxygen/assets/logo_fdio.png b/doxygen/assets/logo_fdio.png
new file mode 100644
index 00000000000..ddfef2c7335
--- /dev/null
+++ b/doxygen/assets/logo_fdio.png