Minor code cleanup and robustness improvement.

- scripts/gitsch2ppm, scripts/schhist2web: replace awkward and cryptic
  `dirname "$x"`/`basename "$x" .old`.new
  construct with much more friendly "${x%.old}.new"
- scripts/gitenealogy: put -- before path names in git-log, to prevent
  parsing ambiguities

scripts/gitenealogy

@@ -37,7 +37,7 @@ if [ ! -f "$1/$2" ]; then
 fi
 
 cd "$1" || exit
-git log --follow --name-status "$2" |
+git log --follow --name-status -- "$2" |
     awk '
 /^commit /{ if (c) print c, n; c = $2 }
 { if (NF) n = $(NF) }

scripts/gitsch2ppm

@@ -32,7 +32,7 @@ EOF
 	gs -sDEVICE=ppmraw -sOutputFile=- -g$IRES -r$res \
 	  -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -q - |
 	  pnmflip -r270 |
-	  cat >`dirname "$1"`/`basename "$1" .ps`.ppm
+	  cat >"${1%.ps}.ppm"
 }
 
 
@@ -111,7 +111,7 @@ if ! $cache; then
     (
 	cd "$sch" || exit
 	rm -f *.ps *.ppm
-	$sanitize "$tmp"/`dirname "$schem"`/`basename "$schem" .sch`.pro ||
+	$sanitize "$tmp/${schem%.sch}.pro" ||
 	  exit
 	eeschema --plot "$tmp/$schem"
     ) || exit

scripts/schhist2web

@@ -89,12 +89,12 @@ else
 fi
 
 if [ ! -z "$1" -a -f "$dir/$1" -a \
-  -f "$dir"/`dirname "$1"`/`basename "$1" .sch`.pro ]; then
+  -f "$dir/${1%.sch}.pro" ]; then
     sch="$1"
     shift
 else
     for n in "$dir"/*.sch; do
-	[ -f `dirname "$n"`/`basename "$n" .sch`.pro ] || continue
+	[ -f "${n%.sch}.pro" ] || continue
 	if [ ! -z "$sch" ]; then
 	    echo "multiple choices for top-level .sch file" 1>&2
 	    exit 1