Enumify terrain blockage and generalize the line of sight function

This should probably be two separate commits, but they're tangled together and I don't want to spend the effort to disentangle them.

osx/classes/simpletypes.h

@@ -240,6 +240,20 @@ enum eTrimType {
 	TRIM_CITY = 18, // the game will join roads up to this space but not draw roads on the space
 };
 
+/*      terrain type blockage          */
+enum class eTerObstruct {
+	CLEAR = 0,
+	BLOCK_SIGHT = 1,
+	BLOCK_MONSTERS = 2,
+	BLOCK_MOVE = 3,
+	BLOCK_MOVE_AND_SHOOT = 4,
+	BLOCK_MOVE_AND_SIGHT = 5,
+};
+
+inline bool blocksMove(eTerObstruct block) {
+	int code = (int) block;
+	return code > 2;
+}
 
 /*      items[i].type    a.k.a type of weapon         */
 enum class eWeapType {

osx/classes/terrain.cpp

@@ -95,7 +95,7 @@ cTerrain& cTerrain::operator = (legacy::terrain_type_type& old){
 		99,99,99,99,99,2, 99,99,99,99,  99,99,99,99,
 	};
 	picture = old.picture;
-	blockage = old.blockage;
+	blockage = (eTerObstruct) old.blockage;
 	if(picture < 260){
 		combat_arena = arenas[picture];
 		ground_type = ground[picture];
@@ -365,3 +365,16 @@ std::istream& operator >> (std::istream& in, eTerSpec& e){
 	else e = TER_SPEC_NONE;
 	return in;
 }
+
+std::ostream& operator << (std::ostream& out, eTerObstruct& e){
+	return out << (int) e;
+}
+
+std::istream& operator >> (std::istream& in, eTerObstruct& e){
+	int i;
+	in >> i;
+	if(i > 0 && i < 6)
+		e = (eTerObstruct) i;
+	else e = eTerObstruct::CLEAR;
+	return in;
+}

osx/classes/terrain.h

@@ -24,7 +24,7 @@ class cTerrain {
 public:
 	std::string name;
 	pic_num_t picture;
-	unsigned char blockage;
+	eTerObstruct blockage;
 	ter_flag_t flag1;
 	ter_flag_t flag2;
 	ter_flag_t flag3; // new additional flag for special properties
@@ -52,5 +52,7 @@ public:
 
 std::ostream& operator << (std::ostream& out, eTerSpec& e);
 std::istream& operator >> (std::istream& in, eTerSpec& e);
+std::ostream& operator << (std::ostream& out, eTerObstruct& e);
+std::istream& operator >> (std::istream& in, eTerObstruct& e);
 
 #endif