1. Cursor API to scan the key space
2. Stream API
   * Read range from streams
   * Trim stream
3. Server Events API to register to the following events:
   * Flush started/ended
   * Loading started/ended for AOF/RDB/Replication
   * Role changed (become primary/replica)
4. Is primary API was added to Context object

Co-authored-by: Omer Shadmi <76992134+oshadmi@users.noreply.github.com>

…es and avoid crashes.

…inary arguments.

Within the macro_rules! the $crate should be used when it is required to
refer to the current crate.
This commit changes the referencing to the correct one.

1. Fixes the warning of the unused result. Now the result is explicitly
   dropped and so the intention behind the code written is clear.
2. Fixes the typo - "emmutable" to "immutable".

By deriving Ord and PartialOrd we can compare two versions easier.
We need to be able to compare the versions to make sure the compatible
version is used with the module.

…bility-checking

Allow for easier version compatibility checking.

Such situations occur when, for example, the crate which uses
the redismodule-rs crate as a dependency is run for testing, so
without Redis available. In this case, there is no allocator available
as well and it will lead to a panic. To enable both the situations to
work correctly under all circumstances, this change introduces a
fallback mechanism back to the system allocator (default Rust allocator)
which is always available.

Note that the changes are zero-cost: the code before this changes used
unwrap() which also had checks for the value being non-null and would
panic at runtime if it was null, the current code does this check as
well but instead of panicking reverts back to the system allocator.

The previous code either wouldn't compile or wouldn't run due to missing
assets for the tests. This commit brings changes necessary to enable the
cargo test to run properly again.

Reverts the behaviour to panicking when the redis allocator isn't
present. Changes the panic to avoid allocations using the specified
allocator so that a meaningful message can be observed.

…allocator-when-redis-isnt-available

Allow the crate to operate when the Redis API isn't available.

The backwards compatibility is broken with the old Rust due to fixing a
mistake with imports. This commit uses the direct import for unix
systems of the AsRawFd trait and should work on all unix systems.

Fix the backwards compatibility with old Rust.