This commit introduces the internal accounting logic for accrueing
multiplier points, that will later be used to determine how many
experience points an account is eligible to.
The majority of the work here was done by @3esmit.
This commit introduces `MIN_LOCKUP_PERIOD` and `MAX_LOCKUP_PERIOD` and
makes use of them within `StakeManager.stake()` and
`StakeManager.lock()` accordingly.
When users deposit tokens into their vault via `stake()`, they can
provide an optional lockup time. If the value is `0` it implies users do
not want to lock their stake.
If the value is `> 0` it has to be within the range of
`MIN_LOCKUP_PERIOD` and `MAX_LOCKUP_PERIOD`.
Properly addresses #15
This commit introduces a first version of a `VaultFactory` that later
will be extended to be capable of instantiating reward vaults and
possible keep track of vault instances per owner.
As a first step, this implementation comes with a `createVault()`
function which takes care of creating vaults.
Because `VaultFactory` also knows about `StakeManager` it can derive the
manager's address and stake token from it when creating vaults, allowing
the API to be without arguments.
Partially addresses #37
Because the `stakedToken` property is `immutable`, solhint recommends to
make it in all caps. This commit changes the property to adhere to that
rule and also makes the property private.
To access the `stakedToken` there's now a `stakedToken()` function on
the contract.