Improve gitignore and add missing test index files

.gitignore

@@ -1,7 +1,7 @@
 deb_dist
 build
 dist
-.gitignore
+#.gitignore
 *~
 *.aux
 *.sbd

test/test_index/.gitignore

@@ -0,0 +1,2 @@
+!*.sxd
+!*.sbx

test/test_index/idx_auth.sbx

@@ -0,0 +1,26 @@
+\begin{idxblock}{A}
+  \idxentry{
+                \indexauthor{}{Aba}
+            }{
+                \hyperlink{song1-4.2}{4}
+            }  \idxentry{
+                \indexauthor{}{Äbc}
+            }{
+                \hyperlink{song1-2.2}{2}
+            }  \idxentry{
+                \indexauthor{}{Abd}
+            }{
+                \hyperlink{song1-3.2}{3}
+            }
+\end{idxblock}
+\begin{idxblock}{J}
+  \idxentry{
+                \indexauthor{}{Jack}
+            }{
+                \hyperlink{song1-1.2}{1}
+            }  \idxentry{
+                \indexauthor{}{Johns}
+            }{
+                \hyperlink{song1-1.2}{1}
+            }
+\end{idxblock}

test/test_index/idx_auth.sxd

@@ -0,0 +1,19 @@
+AUTHOR INDEX DATA FILE
+%ignore unknown
+%after by
+%sep and
+Jack and Johns
+1
+song1-1.2
+Äbc
+2
+song1-2.2
+Abd
+3
+song1-3.2
+Aba
+4
+song1-4.2
+unknown
+5
+song1-5.2

test/test_index/idx_title.sbx

@@ -0,0 +1,22 @@
+\begin{idxblock}{C}
+  \idxentry{
+                \indextitle{}{Caa}
+            }{
+                \hyperlink{song1-3.2}{3}
+            }  \idxentry{
+                \indextitle{}{Çab}
+            }{
+                \hyperlink{song1-2.2}{2}
+            }  \idxentry{
+                \indextitle{}{Cac}
+            }{
+                \hyperlink{song1-4.2}{4}
+            }
+\end{idxblock}
+\begin{idxblock}{M}
+  \idxentry{
+                \indextitle{}{My song}
+            }{
+                \hyperlink{song1-1.2}{1}
+            }
+\end{idxblock}

test/test_index/idx_title.sxd

@@ -0,0 +1,13 @@
+TITLE INDEX DATA FILE
+My song
+1
+song1-1.2
+Çab
+2
+song1-2.2
+Caa
+3
+song1-3.2
+Cac
+4
+song1-4.2