add tool to sort .gitignore content

We sort with lines starting with # first.
We sort with lines starting with * second.
We sort with lines that do not start with [#!*] third.
We sort with lines starting with ! fourth.

Example usage in vim with a keyboard macro <escape>f:

```vim
:map ^[f 1G!G../../bin/sgi^M
```

 or via .vimrc:

```vimrc
" sort the entire .gitignore file using ../../bin/sgi
:map  ^[f 1G!G../../bin/sgi^M
```

 NOTE: The ^[ above is ((Escape)) and ^M is ((Control-M)).

Example usage in shell:

```sh
rm -f t && ../../bin/sgi < .gitignore > t && mv -f t .gitignore
```

Suggested usage:

```sh
bin/all-run.sh bin/sort.gitignore -v 1
```

Sorted all winner .gitignore according to this method.
Sorted all year level .gitignore according to this method.
Sorted top level .gitignore according to this method.

2001/.gitignore

@@ -1,4 +1,4 @@
 #
-# sort with: sort -d -u
+# sort with: ../bin/sgi
 mkentry
 mkentty.o

2001/anonymous/.gitignore

@@ -1,5 +1,6 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 anonymous
 anonymous.bed
 anonymous.bed.alt
@@ -7,7 +8,6 @@ anonymous.orig
 anonymous.ten
 anonymous.ten.32
 anonymous.ten.alt
-*.dSYM
 indent
 indent.c
 indent.o

2001/bellard/.gitignore

@@ -1,9 +1,9 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 bellard
 bellard.orig
 bellard.otccex
-*.dSYM
 indent
 indent.c
 indent.o

2001/cheong/.gitignore

@@ -1,8 +1,8 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 cheong
 cheong.orig
-*.dSYM
 indent
 indent.c
 indent.o

2001/coupard/.gitignore

@@ -1,8 +1,8 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 coupard
 coupard.orig
-*.dSYM
 indent
 indent.c
 indent.o

2001/ctk/.gitignore

@@ -1,8 +1,8 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 ctk
 ctk.orig
-*.dSYM
 indent
 indent.c
 indent.o

2001/dgbeards/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 dgbeards
 dgbeards.alt

2001/herrmann1/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 error
 herrmann1

2001/herrmann2/.gitignore

@@ -1,8 +1,8 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
+*.dSYM
 cup.out
 cup.out2
-*.dSYM
 herrmann2
 herrmann2.orig
 indent

2001/jason/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/kev/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/ollinger/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/rosten/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/schweikh/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/westley/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c

2001/williams/.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: sort -d -u
+# sort with: ../../bin/sgi
 *.dSYM
 indent
 indent.c