Simplify files: sections

Merge all files:group sections into one, where key is name of the group
and value is source name, optionally followed by destination path.

This breaks old mkit.ini's, but significantly simplifies future ones.

 1. Only one section is needed,

 2. group list is implied from the files section, removing the need
    of lists:group,

 3. destination path has been made optional (by default, basename of
    the source path is used).

src/include/deploy.sh

     #
     local grp=$1
     local src=$2
-    echo "$(_get_root "$grp")/$(ini 1value "files:$grp:$src")"
+    local dst=$3
+    test -n "$dst" || dst=${src##*/}
+    echo "$(_get_root "$grp")/$dst"
 }
 
 _get_root() {
     # Install product
     #
     local dst group mode src
-    ini values "lists:group" \
+    ini lskeys "files" \
+      | sort \
+      | uniq \
       | while read group;
         do
             mode=$(ini 1value "modes:$group")
-            ini lskeys "files:$group" \
-              | while read src;
+            ini values "files:$group" \
+              | while read src dst;
                 do
-                    dst=$(_get_dst "$group" "$src")
+                    dst=$(_get_dst "$group" "$src" "$dst")
                     _deploy_item "$src" "$dst" "$mode"
                 done
         done
     # Uninstall product
     #
     local dst group src
-    ini values "lists:group" \
+    ini lskeys "files" \
+      | sort \
+      | uniq \
       | while read group;
         do
-            ini lskeys "files:$group" \
-              | while read src;
+            ini values "files:$group" \
+              | while read src dst;
                 do
-                    dst=$(_get_dst "$group" "$src")
+                    dst=$(_get_dst "$group" "$src" "$dst")
                     _maybe rm -vrf "$dst"
                 done
         done