Add TeX4ht build script.

diff --git a/convert_tex4ht b/convert_tex4ht
new file mode 100755 (executable)
index 0000000..b645b4e
--- /dev/null
+++ b/convert_tex4ht
@@ -0,0 +1,12 @@
+#!/bin/sh
+set -e
+
+# Output is XHTML, document character encoding will be UTF-8.
+OPTIONS1="xhtml,charset=utf-8"
+
+# Yes, that first whitespace character is meant to be there.
+# unicode support, generate unicode characters instead of escape codes, environment file.
+OPTIONS2=" -cunihtf -utf8"
+
+mk4ht xhlatex ./relat10.tex "${OPTIONS1}" "${OPTIONS2}"
+ebook-convert relat10.html "Einstein - Relativity.mobi"