Upgrade to CSS4J 1.0.0 RC3

Version 1.0.0-rc3
-----------------
 * Core:
- DOM impl.: make name character verification stricter.
- DOM impl./Wrapper: if an element contains an entity reference, remove the 
  requirement that it contains no child nodes for the element to not match
  :blank or :empty.
- CSSOM: API CHANGE: change the types returned by 
  CSSComputedProperties.getComputedFontSize() and StyleDatabase.getExSizeInPt() 
  to a float.
- CSSOM: do not provide SAC nor NSAC as a service: the chances of a second NSAC
  implementation appearing are remote, and you generally want to control which
  SAC parser you are using.
- CSSOM: AlgebraicExpression and CSSOperandExpression now extend CSSExpression.
- CSSOM: add writeCssText(SimpleWriter) to CSSExpression.
- CSSOM: initial support for evaluating functions and calc() expressions in 
  computed styles.
- CSSOM: small improvements to NumberValue.
- CSSOM: sheet error handler: an empty style rule is a warning, not an error 
  (was counting as both).
- CSSOM: when serializing alpha channel of RGBColor value, turn off digit 
  grouping just in case.

 * Dom4j module:
- Adapt to API CHANGE in core module.

 * AWT module:
- Adapt to API CHANGE in core module.

Version 1.0.0-rc2
-----------------
 * Core:
- NSAC impl.: improve colour parsing (fixes a bug parsing 4- and 8-digit hex
  values).
- NSAC impl.: better error message for malformed rgb()/rgba()/hsl() colors.
- CSSOM: fix a bug serializing color values with alpha channel.
- DOM impl.: add method serializeToString(Node) to DOMWriter.
- CSSOM: add method hasOMWarnings() to SheetErrorHandler.
- CSSOM: rename the remaining CSS-prefixed primitive types.
- Util: set up an initial capacity of 128 in the BufferSimpleWriter default
  constructor.
- Maven POM: update source control settings due to Github migration.
- Maven POM: add a section to deploy to Github.
- Replace Sourceforge URLs for Github's.
- Add a README.

 * Dom4j module:
- Method hasOMWarnings() was added to SheetErrorHandler.
- Remove unnecessary usage of specialized type in style declaration test.
- Maven POM: update source control settings due to Github migration.
- Maven POM: update dom4j dependency to 2.1.1 so the vulnerability scanner stops
  complaining.
- Maven POM: add a section to deploy to Github.
- Replace Sourceforge URLs for Github's.
- Add a README.

 * Agent module:
- Maven POM: update source control settings due to Github migration.
- Maven POM: add a section to deploy to Github.
- Replace Sourceforge URLs for Github's.
- Add a README.

 * AWT module:
- Small cleanup.
- Maven POM: update source control settings due to Github migration.
- Maven POM: add a section to deploy to Github.
- Replace Sourceforge URLs for Github's.
- Add a README.