Rename bg to bg+phonetic

The 'bg' layout is actually the 'bg+phonetic' layout.
Mark it as such.

data/keyboards/bg.yaml

@@ -1,78 +0,0 @@
----
-outlines:
-    default: { width: 32.72, height: 52 }
-    altline: { width: 47, height: 52 }
-    wide: { width: 49.09, height: 52 }
-    spaceline: { width: 185, height: 52 }
-    special: { width: 44, height: 52 }
-
-views:
-    base:
-        - "я в е р т ъ у и о п ю"
-        - "а с д ф г х й к л ш щ"
-        - "Shift_L з ь ц ж б н м ч BackSpace"
-        - "show_numbers preferences         space   .    Return"
-    upper:
-        - "Я В Е Р Т Ъ У И О П Ю"
-        - "А С Д Ф Г Х Й К Л Ш Щ"
-        - "Shift_L З Ь Ц Ж Б Н М Ч BackSpace"
-        - "show_numbers preferences         space   ,    Return"
-    numbers:
-        - "1 2 3 4 5 6 7 8 9 0"
-        - "@ # € % & - _ + ( )"
-        - "show_symbols   , \" ' colon ; ! ?  BackSpace"
-        - "show_letters preferences         space        Return"
-    symbols:
-        - "~ ` | · √ π τ ÷ × ¶"
-        - "© ® £ $ ¥ ^ ° * { }"
-        - "show_numbers_from_symbols   \\ / < > = [ ]  BackSpace"
-        - "show_letters preferences         space        Return"
-
-
-buttons:
-    Shift_L:
-        action:
-            locking:
-                lock_view: "upper"
-                unlock_view: "base"
-        outline: "altline"
-        icon: "key-shift"
-    BackSpace:
-        outline: "altline"
-        icon: "edit-clear-symbolic"
-        action: erase
-    preferences:
-        action: "show_prefs"
-        outline: "special"
-        icon: "keyboard-mode-symbolic"
-    show_numbers:
-        action:
-            set_view: "numbers"
-        outline: "wide"
-        label: "123"
-    show_numbers_from_symbols:
-        action:
-            set_view: "numbers"
-        outline: "altline"
-        label: "123"
-    show_letters:
-        action:
-            set_view: "base"
-        outline: "wide"
-        label: "abc"
-    show_symbols:
-        action:
-            set_view: "symbols"
-        outline: "altline"
-        label: "*/="
-    space:
-        outline: "spaceline"
-        text: " "
-    Return:
-        outline: "wide"
-        icon: "key-enter"
-        keysym: "Return"
-    colon:
-        text: ":"
-    "\"":
-        keysym: "quotedbl"