Gear test lib

[breathx]

Resolves #577. Closes #570 and closes #571 as not actual, because they're implemented in the lib.

Release Notes: It is a very handy tool that allows for total testing of the smart contract logic.
You can easily initialize the programs, send the messages and check the execution result in the log. The log can be checked for a specific message generated by the program execution and that's great since there may be several messages and it may be necessary to check not the last message, but some message that occurred during the program execution.
The tool makes it possible to increase the blockchain time and thus test the time-dependent logic in smart contracts. It also includes a helpful feature like creating mock contracts.

[shamilsan]

Awesome as an MVP but needs to be reviewed while adopting.

[LouiseMedova]

It is a very handy tool that allows for total testing of the smart contract logic.
You can easily initialize the programs, send the messages and check the execution result in the log. The log can be checked for a specific message generated by the program execution and that's great since there may be several messages and it may be necessary to check not the last message, but some message that occurred during the program execution.
The tool makes it possible to increase the blockchain time and thus test the time-dependent logic in smart contracts. It also includes a helpful feature like creating mock contracts.

[shamilsan]

Excellent!

[NikVolf]

It is a very handy tool that allows for total testing of the smart contract logic.
You can easily initialize the programs, send the messages and check the execution result in the log. The log can be checked for a specific message generated by the program execution and that's great since there may be several messages and it may be necessary to check not the last message, but some message that occurred during the program execution.
The tool makes it possible to increase the blockchain time and thus test the time-dependent logic in smart contracts. It also includes a helpful feature like creating mock contracts.

this looks like it worth putting as release notes @breathx