This commit makes use of the new btcutil.AppDataDir function which chooses
appropriate data directories for each supported operating system. It also
adds code to the upgrade path to properly migrate existing data from the
old to new locations.
This is part of work toward issue #30.
This commit modifies the way the data paths are handled. Since there will
ultimately be more data associated with each network than just the block
database, the data path has been modified to be "namespaced" based on the
network. This allows all data associated with a specific network to
simply use the data path without having to worry about conflicts with data
from other networks.
In addition, this commit renames the block database to "blocks" plus a
suffix which denotes the database type. This prevents issues that would
otherwise arise if the user decides to use a different database type and
a file/folder with the same name already eixsts but is of the old database
type. For most users this won't matter, but it does provide nice
properties for testing and development as well since it makes it easy to
go back and forth between database types.
This commit also includes code to upgrade the old database paths to the
new ones so the change is seamless for the user.
Finally, bump the version to 0.2.0.
This commit adds a basic infrastructure to allow upgrades to happen to
btcd as needed. This paves the way for the upcoming data path changes to
be automatically updated for the user as needed and also ensures any
future changes that might require upgrades already have an established
way of performing the needed upgrades.
