ENH: Improved table node

• Changed table schema column name: "name" column in table schema looked like a regular property, it was not obvious that it refers to column name.
  "columnName" is now used instead, to make the reference more explicit.
• Fixed copy-paste of bit type cells displayed as (checkboxes)
• Updated documentation
• Improved log messages and fixed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@26053 3bd1e089-480b-0410-8dfb-8563597acbee