Description
Right now, the mode downloads the Android SDK to the sdk subfolder inside the mode folder. The SDK could easily be more than 1GB in size after installing emulator's system images. However, when the mode is updated through the CM, the old version is moved into a temporary folder, so the user (if he or she does not move the SDK files back into the folder of the updated mode) will have to download the SDK again. The SDK download dialog will be in fact triggered right after updating the mode (since the PDE will try to load it, but the SDK is gone).
If the SDK were to be dowloaded in the sketchbook's root folder, this will not happen. Currently, the release keystore is being saved there, as /keystore/android-release-key.keystore, so perhaps we could put both keystore and sdk (and also the avds created by the mode) inside /android, so all android-related dependencies are aggregated under the same location. This of course will not happen if the user is using the environment's SDK (although it will still save the keystore inside the sketchbook).
Other locations to save the SDK to could be the /Library, where Processing currently saves its preferences to. A problem of using these folders that are by default hidden to the user to store the Android SDK is that they would end up holding several GBs, and the user may have trouble finding them. By storing them in the sketchbook folder, users should be able to easily remove the SDK if it is no longer needed.