system/eskin: Post-SVN clean up

- Move source code from `trunk` into program root directory.
- Update build files.

data/Tupfile.lua

@@ -420,7 +420,7 @@ tup.append_table(img_files, {
  {"DEFAULT.SKN", VAR_SKINS .. "/../skins/Leency/Shkvorka/Shkvorka.skn"},
  {"DISPTEST", VAR_PROGS .. "/testing/disptest/trunk/disptest"},
  {"END", VAR_PROGS .. "/system/end/light/end"},
- {"ESKIN", VAR_PROGS .. "/system/eskin/trunk/eskin"},
+ {"ESKIN", VAR_PROGS .. "/system/eskin/eskin"},
  {"FSPEED", VAR_PROGS .. "/testing/fspeed/fspeed"},
  {"GMON", VAR_PROGS .. "/system/gmon/gmon"},
  {"HDD_INFO", VAR_PROGS .. "/system/hdd_info/trunk/hdd_info"},