Extension Builder

This is part of the roundtrip concept but could be useful also for current trunk: It should be possible to configure overwrite settings via Typoscript.
Simple example: If you added an ext_icon.gif it will be overriden each time you save in the kickstarter.

I attached a patch which adds a Typoscript setup:

### overwrite settings only apply if this flag is set to true
enableRoundtrip = 0

### an array representing the file structure of the extension, where each file can be configured separately.
# 0 always overwrite
# 1 merge (if possible)
# 2 never overwrite
#######################################
settings.roundtrip.overWriteSettings{
        ext_icon.gif = 2
    Resources {
        Private {
            Language {
                locallang_db.xml = 0
                locallang.xml = 2
            }
        }
    }
    etc.
}