Added "unknown" atlas format and filter enum value.

closes #515

spine-c/include/spine/Atlas.h

@@ -39,6 +39,7 @@ extern "C" {
 typedef struct spAtlas spAtlas;
 
 typedef enum {
+	SP_ATLAS_UNKNOWN_FORMAT,
 	SP_ATLAS_ALPHA,
 	SP_ATLAS_INTENSITY,
 	SP_ATLAS_LUMINANCE_ALPHA,
@@ -49,6 +50,7 @@ typedef enum {
 } spAtlasFormat;
 
 typedef enum {
+	SP_ATLAS_UNKNOWN_FILTER,
 	SP_ATLAS_NEAREST,
 	SP_ATLAS_LINEAR,
 	SP_ATLAS_MIPMAP,
@@ -59,7 +61,9 @@ typedef enum {
 } spAtlasFilter;
 
 typedef enum {
-	SP_ATLAS_MIRROREDREPEAT, SP_ATLAS_CLAMPTOEDGE, SP_ATLAS_REPEAT
+	SP_ATLAS_MIRROREDREPEAT,
+	SP_ATLAS_CLAMPTOEDGE,
+	SP_ATLAS_REPEAT
 } spAtlasWrap;
 
 typedef struct spAtlasPage spAtlasPage;

spine-c/src/spine/Atlas.c

@@ -145,7 +145,7 @@ static int indexOf (const char** array, int count, Str* str) {
 	int i;
 	for (i = count - 1; i >= 0; i--)
 		if (strncmp(array[i], str->begin, length) == 0) return i;
-	return -1;
+	return 0;
 }
 
 static int equals (Str* str, const char* other) {