Manual initialization

[scudette]

Initialization is automatically done in init() function. This means that even if the binary knows it is not going to use the files (e.g. through command line options) the data will still be unpacked into memory. This wastes memory and slows down start up time.

It would be really good if an option could be added to export an init function which must be called manually to build the webdav FS object for the first time.