merge trunk changes through r1258

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/branches/jdk8@1259 f203690c-595d-4dc9-a70b-905162fa7fd2

diff --cc src/changes/changes.xml
Simple merge

diff --cc src/main/java/com/healthmarketscience/jackcess/DataType.java
Simple merge

diff --cc src/main/java/com/healthmarketscience/jackcess/impl/CalculatedColumnUtil.java
Simple merge

diff --cc src/main/java/com/healthmarketscience/jackcess/impl/ColumnImpl.java
index 41728746ce3fa88c7d746eae5835fd3a82d4f300,3445ba3d3ee95f1b3fd2ad1eca1fb1a867985276..212b912917c1ea9db083ec9c3b4b50cf4d0abebc
--- 1/src/main/java/com/healthmarketscience/jackcess/impl/ColumnImpl.java
--- 2/src/main/java/com/healthmarketscience/jackcess/impl/ColumnImpl.java
+++ b/src/main/java/com/healthmarketscience/jackcess/impl/ColumnImpl.java
@@@ -468,12 -433,17 +472,19 @@@ public class ColumnImpl implements Colu
      return _columnLength;
    }
  
-   public short getLengthInUnits() {
-     return (short)getType().toUnitSize(getLength());
 +  @Override
+   public final short getLengthInUnits() {
+     if(_lengthInUnits == INVALID_LENGTH) {
+       _lengthInUnits = calcLengthInUnits();
+     }
+     return (short)_lengthInUnits;
+   }
+ 
+   protected int calcLengthInUnits() {
+     return getType().toUnitSize(getLength(), getFormat());
    }
  
 +  @Override
    public boolean isCalculated() {
      return _calculated;
    }