#109 Gracefully handle partial prefs file at startup

[Code-Breaker]

Currently, if no prefs file is found, all defaults are used. In the case of a partial prefs file, no defaults are used and those missing prefs are left blank. This should be changed so that any missing values are defaulted.

Usecase: I want to automate setup using a script, and I only need to change a few prefs from default. I could create a partial prefs file with only those non-default settings, run davmail, and all other non-specified prefs would fall back to defaults.

This could be accomplished by loading all defaults first, then reading the prefs file and replacing any prefs with values found. I don't see any downside to this approach, since the way it works now (blank values) is never useful.

[Mickael Guessant]

Some settings have a default value, however others don't.

In your case another approach would be to use the example davmail.properties and script individual property change, e.g. with ant:

<replaceregexp file="path/to/davmail.properties"
               match="^davmail.keepDelay=.*"
               replace="davmail.keepDelay=60"
               byline="true"/>