Removed more extraneous files

SA_DiceErrorHandling.h

-//
-//  SA_DiceErrorHandling.h
-//
-//	Copyright (c) 2016 Said Achmiz.
-//
-//	This software is licensed under the MIT license.
-//	See the file "LICENSE" for more information.
-
-#import <Foundation/Foundation.h>
-
-@interface SA_DiceErrorHandler : NSObject
-
-+(void) addError:(NSString *)error
-	toExpression:(NSMutableDictionary *)expression;
-
-+(void) addErrorsFromExpression:(NSDictionary *)sourceExpression
-				   toExpression:(NSMutableDictionary *)targetExpression;
-
-+(NSArray <NSString *> *) errorsForExpression:(NSDictionary *)expression;
-
-@end

SA_DiceErrorHandling.m

-//
-//  SA_DiceErrorHandling.m
-//
-//	Copyright (c) 2016 Said Achmiz.
-//
-//	This software is licensed under the MIT license.
-//	See the file "LICENSE" for more information.
-
-#import "SA_DiceErrorHandling.h"
-
-#import "SA_DiceExpressionStringConstants.h"
-
-@implementation SA_DiceErrorHandler
-
-+(void) addError:(NSString *)error
-	toExpression:(NSMutableDictionary *)expression {
-	if (error == nil || expression == nil) {
-		return;
-	}
-
-	if (expression[SA_DB_ERRORS] == nil) {
-		expression[SA_DB_ERRORS] = [NSMutableArray <NSString *> arrayWithObjects:error, nil];
-	} else {
-		[expression[SA_DB_ERRORS] addObject:error];
-	}
-}
-
-// Top-level errors only (i.e. the expression tree is not traversed in search
-// of deeper errors).
-+(void) addErrorsFromExpression:(NSDictionary *)sourceExpression
-				   toExpression:(NSMutableDictionary *)targetExpression {
-	if (sourceExpression == nil || targetExpression == nil) {
-		return;
-	}
-
-	if (sourceExpression[SA_DB_ERRORS] == nil || [sourceExpression[SA_DB_ERRORS] count] == 0) {
-		// Do absolutely nothing; no errors to add.
-	} else if(targetExpression[SA_DB_ERRORS] == nil) {
-		targetExpression[SA_DB_ERRORS] = [NSMutableArray <NSString *> arrayWithArray:sourceExpression[SA_DB_ERRORS]];
-	} else {
-		[targetExpression[SA_DB_ERRORS] addObjectsFromArray:sourceExpression[SA_DB_ERRORS]];
-	}
-}
-
-+(NSArray <NSString *> *) errorsForExpression:(NSDictionary *)expression {
-	return ([expression[SA_DB_ERRORS] count] > 0) ? expression[SA_DB_ERRORS] : nil;
-}
-
-
-@end