sysdbql(7): Fixed example LIST output.
ReleaseNotes: Fixed date of the 0.2.0 release.
frontend, proto: Include object type in FETCH and LOOKUP messages.

The respective commands only support hosts at the moment but this change
prepares the wire-format to support other types as well.
frontend/proto.h: Improved documentation of all message types.
object: Assert that object's are not free'd multiple times.

Else, we'd access free'd memory when trying to do so.
utils dbi: Guard against multiple calls to dbi_shutdown_r().

This should not happen anyway but better be safe than sorry.
store_lookup: Fixed parsing of invalid compare expressions.

Previously, expressions like 'host.foo != 123' would be silently accepted by
the parser.

Added test cases to reproduce and catch the problem.
data: Ensure a stable ordering in cmp() in case of type-mismatches.

So far, this doesn't make a difference but it's better style anyway.
store_lookup: Fixed lookup by back-end name.

Added an integration test which reproduces the problem -- previously, all
compare operations reported a mismatch.
data: Format NULL values as "<NULL>".
data: Added sdb_data_isnull().

The function determines if a datum pointer or a string or binary datum is
NULL.
data: Use %g format when formatting decimal numbers.

This is much better human-readable and we don't need an exact representation.
In fact, given that a datum's string value is used when comparing attribute
values, the human readable format is much better suited given that chances are
higher that users will enter numbers in the same format (but it's still just a
best guess kind of thing).
data: Added sdb_data_strcmp().

This function compares the string values of two data points.
store_lookup: Compare attribute string values on type mismatch.

Given that we don't support any schema for attribute values, this sounds like
a better option than assuming that those values never match no matter which
comparison operator is used.