Update variant names of Element enum

These had been based on the "ZZT file format" wiki article, but Weave
came up with some nicer unofficial names for the elements that ZZT 3.2
left unnamed. The variants are still named in CamelCase; this commit
just makes them a little closer to what they're called in practice.

Also in this commit: capitalize letters when they stand for directions
in names, like `SliderEW` (instead of `SliderEw`, which sounds like
expressing disgust over slider puzzles).

src/elements.rs

@@ -18,7 +18,7 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[repr(u8)]
 pub enum Element {
     Empty = 0,
-    BoardEdge = 1,
+    Edge = 1,
     Messenger = 2,
     Monitor = 3,
     Player = 4,
@@ -42,15 +42,15 @@ pub enum Element {
     Normal = 22,
     Breakable = 23,
     Boulder = 24,
-    SliderNs = 25,
+    SliderNS = 25,
-    SliderEw = 26,
+    SliderEW = 26,
     Fake = 27,
     Invisible = 28,
     BlinkWall = 29,
     Transporter = 30,
     Line = 31,
     Ricochet = 32,
-    BlinkRayH = 33,
+    BlinkEW = 33,
     Bear = 34,
     Ruffian = 35,
     Object = 36,
@@ -60,15 +60,15 @@ pub enum Element {
     Pusher = 40,
     Lion = 41,
     Tiger = 42,
-    BlinkRayV = 43,
+    BlinkNS = 43,
     Head = 44,
     Segment = 45,
     // 46 is unused
-    TextBlue = 47,
+    BlueText = 47,
-    TextGreen = 48,
+    GreenText = 48,
-    TextCyan = 49,
+    CyanText = 49,
-    TextRed = 50,
+    RedText = 50,
-    TextPurple = 51,
+    PurpleText = 51,
-    TextBrown = 52,
+    BrownText = 52,
-    TextBlack = 53,
+    WhiteText = 53,
 }