Bug 180842 Config memory buffer size in data engine execution.
To tuning the performance, it is necessary for DtE to expose API for clients to config the size of memory it used to store the final result set. A new AppContext string, "org.eclipse.birt.data.cache.memory.size" is proposed. The new appcontext entry only accept positive integer as input, the unit of which would be MB.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/i18n/ResourceConstants.java
public final static String BAD_PARAM_TYPE = "data.engine.BadParameterType";
	public final static String NO_SOLUTION_FOUND = "data.engine.NoIrrSolution";
	public final static String EXPECT_BOOLEAN_RETURN_TYPE = "data.engine.BadFetchScriptReturnType";
	public final static String BAD_INTERVAL_UNIT = "data.engine.BadIntervalUnit";
	public final static String INVALID_FIELD_NAME = "data.engine.InvalidFieldName";
	public final static String BAD_GROUP_KEY_TYPE = "data.engine.BadGroupKeyType";
	public final static String BAD_GROUP_INTERVAL_TYPE = "data.engine.group.interval";
	public final static String BAD_GROUP_INTERVAL_TYPE_ROWID = "data.engine.group.interval.Rowid";
	public final static String BAD_GROUP_INTERVAL_INVALID = "data.engine.group.interval.invalid";
	public final static String UNSUPPORTED_FILTER_ON_GROUP="data.engine.NoSupportFilterOnGroup";
	public final static String INVALID_TOP_BOTTOM_ARGUMENT="data.engine.InvalidTopBottomArgument";
	public final static String INVALID_TOP_BOTTOM_N_ARGUMENT="data.engine.InvalidTopBottomNArgument";
	public final static String INVALID_TOP_BOTTOM_PERCENT_ARGUMENT="data.engine.InvalidTopBottomPercentArgument";
	public final static String INVALID_TOP_BOTTOM_N="data.engine.InvalidTopBottomN";
	public final static String INVALID_PERCENTILE_ARGUMENT="data.engine.InvalidPercentileArgument";
	public final static String INVALID_QUARTILE_ARGUMENT="data.engine.InvalidQuartileArgument";
	
	public final static String ILLEGAL_PARAMETER_FUN = "data.engine.BadAggrFuncParam";
	public final static String RESET_RATE = "data.engine.ResetRateGuess";
	public final static String UNSUPPORTTED_COND_OPERATOR = "data.engine.UnsupportedCondOp";
	public final static String EXPRESSION_CANNOT_BE_NULL_OR_BLANK = "data.engine.EmptyExpression";	
			
	public final static String INVALID_JOIN_TYPE="data.engine.InvalidJoinType";
	public final static String INVALID_JOIN_OPERATOR="data.engine.InvalidJoinOperator";
	public final static String NAMED_PARAMETER_NOT_FOUND  = "data.engine.BadDataSetParamName";
	
	
	public final static String INVALID_BOUND_COLUMN_NAME = "data.engine.InvalidBoundColumnName";
	public final static String INVALID_GROUP_KEY = "data.engine.InvalidGroupKey";
	public final static String COLUMN_BINDING_NOT_EXIST = "data.engine.ColumnBindingNotExist";