Added default background color to WebEditorMapper

WebEditorMapper is using "background" theme color as the default
background instead of null.
Added pluginKey="declBoder"
Added 7 mappings

Markdown (winterwell.markdown)
Console (org.eclipse.debug.ui)
CVS (org.eclipse.team.cvs.ui)
Spket JavaScript (com.spket.js)
Spket XML (com.spket.xml)
XSL (org.eclipse.wst.xsl.ui)
DTD (org.eclipse.wst.dtd.ui)
Setting Default BG color in GenericMapper

Promoted definition and setup of Default Background (defaultBackground)
from WebEditorMapper to its parent: WebEditorMapper
Added mapping for e4 CSS

Added E4CSSMapper class and org.eclipse.wst.css.ui map file
Added Markdown Link color mapping
Added "Force Background" preference

An option to set all background colors to the default, which forces the
background color of all color styles to be 'background' color of the
theme.
Change the indentation level to 4 spaces

Replaced tabs in indentation by 4 spaces,
which is what Eclipse Color Theme uses
Code cleanup

Removed a comment
Renamed two functions
Enclosed BufferedReader.read()/BufferedReader.close() in try/finally block
Removed useless else after a return
Fix dangling merge conflict
Merge pull request #136 from jeckhart/fix-merge-conflict

Fix dangling merge conflict
Merge branch 'pakdel-master'

Conflicts:
	com.github.eclipsecolortheme/src/com/github/eclipsecolortheme/preferences/ColorThemePreferencePage.java
Update CHANGES and README
Merged with last master. Not making external new force background setting in preferences page due to conflicts.