Add makefile to build svg diagrams using asciitosvg
diff --git a/book/diagram/.gitignore b/book/diagram/.gitignore
new file mode 100644
index 0000000..81631c6
--- /dev/null
+++ b/book/diagram/.gitignore
@@ -0,0 +1,2 @@
+/bin
+/build
diff --git a/book/diagram/Makefile b/book/diagram/Makefile
new file mode 100644
index 0000000..956d7e0
--- /dev/null
+++ b/book/diagram/Makefile
@@ -0,0 +1,19 @@
+all:
+
+bin/asciitosvg:
+ rm -rf build
+ mkdir -p bin build/src/github.com/asciitosvg/asciitosvg
+ cd build/src/github.com/asciitosvg/asciitosvg && \
+ git init && \
+ git remote add asciitosvg https://github.com/asciitosvg/asciitosvg && \
+ git fetch asciitosvg refs/pull/23/head && \
+ git checkout --quiet 29f2ed76b60231da99ac1d4bca26e8ff93125a2e
+ GOPATH=${CURDIR}/build go build -o $@ ./build/src/github.com/asciitosvg/asciitosvg/cmd/a2s
+
+%.svg: %.ascii bin/asciitosvg
+ bin/asciitosvg -i $< -o $@ -b
+
+clean:
+ rm -f *.svg
+
+.PHONY: all clean
