Bug 211839 String grouping unit type needs to support interval range.
Build ID: I20071101-2000 As Chart has supported, the String grouping unit type can be set interval range, the interval range means that the string group will base on row count distinction. For instance, let's say we have a,b,c,d,e,f,g , and set interval range to 2, the grouping result should be a,c,e,g. Now it is a requirement that DtE support the grouping type.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/i18n/ResourceConstants.java
public final static String INVALID_GROUP_KEY_COLUMN = "data.engine.InvalidGroupKeyName";
	public final static String INVALID_CLOSESCRIPT = "data.engine.BadCloseScript";
	public final static String INVALID_CUSTOM_FIELD_INDEX = "data.engine.InvalidCustomFieldIdx";
	public final static String INVALID_GROUP_NAME = "data.engine.InvalidGroupName";
	public final static String DUPLICATE_GROUP_NAME = "data.engine.DuplicateGroupName";
	public final static String INVALID_OPENSCRIPT = "data.engine.BadOpenScript";
	public final static String DS_HAS_OPENED = "data.engine.DataSourceIsOpen";
	public final static String DS_NOT_OPEN = "data.engine.DataSourceNotOpen";
	public final static String CUSTOM_FIELD_EMPTY = "data.engine.EmptyCustomFieldName";
	public final static String DUP_CUSTOM_FIELD_NAME = "data.engine.DupCustomFieldName";
	public final static String NO_RESULT_SET = "data.engine.NoResultSet";
	public final static String METADATA_NOT_AVAILABLE = "data.engine.NoResultMetadata";
	public final static String QUERY_HAS_PREPARED = "data.engine.QueryAlreadyPrepared";
	public final static String QUERY_HAS_NOT_PREPARED = "data.engine.QueryNotPrepared";
	public final static String INAVLID_FIELD_NAME = "data.engine.InvalidFieldName";
	public final static String DUPLICATE_COLUMN_NAME = "data.engine.DupColumnName";
	public final static String DUPLICATE_ALIAS_NAME = "data.engine.DupAlias";
	public final static String INVALID_FIELD_INDEX = "data.engine.InvalidFieldIndex";
	public final static String INVALID_PERCENTILE_COLUMN = "data.engine.InvalidPercentileColumn";
	
	public final static String MATCH_ERROR = "data.engine.MatchError";
	public final static String UNSUPPORTED_DATA_TYPE = "data.engine.BadOperandType";
	
	public final static String BAD_PARAM_COUNT = "data.engine.BadParameterCount";
	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";