- In getHoldings.WisdomTree, "Weight" colname becomes "XXX.Weight" (where 
  "XXX" is the ticker symbol of the ETF) to match the other getHoldings.* 
  functions.
- duplicated names of holdings are not duplicated in the warning in 
  getHoldings.iShares
- duplicates of "--" do not trigger the duplicate holdings warning in 
  getHoldings.iShares.  The CUSIP column is (and has always been) used for 
  the row names and is what is checked for duplicate holdings; it often 
  contains "--".  The Symbol column would probably be better for most 
  equity ETFs, but non-equity ETFs do not have that column.
- remove Date, Depends, etc. from package level help page.  TODO: write package
  level documentation.

git-svn-id: svn://scm.r-forge.r-project.org/svnroot/twsinstrument/pkg/qmao@392 edb9625f-4e0d-4859-8d74-9fd3b1da38cb