Add 'reinstall' command.

The 'install' command does nothing if the package is detected to be
already installed, but there are circumstances where we will want to
trigger a rebuild and reinstall explicitly. Separate out into two
commands, one of which is a superset of the other.

chocpkg/chocpkg

@@ -167,12 +167,7 @@ build_package() {
     )
 }
 
-install_package() {
+reinstall_package() {
-    # Already installed?
-    if check_installed; then
-        return
-    fi
-
     build_package "$PACKAGE_NAME"
 
     cd "$PACKAGE_BUILD_DIR"
@@ -181,6 +176,13 @@ install_package() {
     )
 }
 
+install_package() {
+    # Already installed? Don't install again.
+    if ! check_installed; then
+        reinstall_package
+    fi
+}
+
 if [ $# -lt 2 ]; then
     echo "Usage: $0 [fetch|build|install|installed] <package name>"
     exit -1
@@ -196,6 +198,9 @@ case "$cmd" in
     build)
         build_package
         ;;
+    reinstall)
+        reinstall_package
+        ;;
     install)
         install_package
         ;;