Substitute DbType.Currency with DbType.Decimal in OracleManagedDataClientDriver and OracleDataClientDriver

- Align DbType.Currency registration in Oracle8iDialect to other dialects & DbType.Currency specification

Fixes #1052

Author: hazzik

src/NHibernate.Test/Async/TypesTest/CurrencyTypeFixture.cs

@@ -26,9 +26,6 @@ protected override string TypeName
 		[Test]
 		public async Task ReadWriteAsync()
 		{
-			if (Dialect is Oracle8iDialect)
-				Assert.Ignore("The Oracle dialect maps currency as Number(20, 2), this test can only fail.");
-
 			const decimal expected = 5.6435M;
 
 			var basic = new CurrencyClass {CurrencyValue = expected};

src/NHibernate.Test/TypesTest/CurrencyTypeFixture.cs

@@ -40,9 +40,6 @@ public void Equals()
 		[Test]
 		public void ReadWrite()
 		{
-			if (Dialect is Oracle8iDialect)
-				Assert.Ignore("The Oracle dialect maps currency as Number(20, 2), this test can only fail.");
-
 			const decimal expected = 5.6435M;
 
 			var basic = new CurrencyClass {CurrencyValue = expected};

src/NHibernate/Dialect/Oracle8iDialect.cs

@@ -182,7 +182,7 @@ protected virtual void RegisterNumericTypeMappings()
 			RegisterColumnType(DbType.UInt32, "NUMBER(10,0)");
 			RegisterColumnType(DbType.UInt64, "NUMBER(20,0)");
 
-			RegisterColumnType(DbType.Currency, "NUMBER(20,2)");
+			RegisterColumnType(DbType.Currency, "NUMBER(22,4)");
 			RegisterColumnType(DbType.Single, "FLOAT(24)");
 			RegisterColumnType(DbType.Double, "DOUBLE PRECISION");
 			// Oracle max precision is 39-40, but .Net is limited to 28-29.

src/NHibernate/Driver/OracleDataClientDriverBase.cs

@@ -129,6 +129,9 @@ protected override void InitializeParameter(DbParameter dbParam, string name, Sq
 					else
 						base.InitializeParameter(dbParam, name, sqlType);
 					break;
+				case DbType.Currency:
+					base.InitializeParameter(dbParam, name, SqlTypeFactory.Decimal);
+					break;
 				default:
 					base.InitializeParameter(dbParam, name, sqlType);
 					break;