rename environ, get_enum, instance and state files to ss_?

src/lib66/environ.c → src/lib66/ss_environ.c

 /* 
- * environ.c
+ * ss_environ.c
  * 
  * Copyright (c) 2018-2020 Eric Vidal <eric@obarun.org>
  * 

src/lib66/get_enum.c → src/lib66/ss_get_enum.c

 /* 
- * get_enum.c
+ * ss_get_enum.c
  * 
  * Copyright (c) 2018-2020 Eric Vidal <eric@obarun.org>
  * 

src/lib66/instance.c → src/lib66/ss_instance.c

 /* 
- * instance.c
+ * ss_instance.c
  * 
  * Copyright (c) 2018-2020 Eric Vidal <eric@obarun.org>
  * 

src/lib66/state.c → src/lib66/ss_state.c

 /* 
- * state.c
+ * ss_state.c
  * 
  * Copyright (c) 2018-2020 Eric Vidal <eric@obarun.org>
  *