v0 coexistence and data type extensibility

[pavel-kirienko]

This pull request implements the changes discussed in https://github.com/UAVCAN/specification/pull/64:

• Implicit zero extension (implicit truncation is the original behavior, no changes needed).
• CAN transport: new CAN ID format that permits coexistence of v1 and v0 on the same CAN bus.
• UDP and Serial transports: data type hash mismatch is no longer considered an error. This is necessary to support polymorphic types. The structure of the data type hash will require reconsideration (https://github.com/UAVCAN/specification/issues/66).

Also, I slightly relaxed the timing requirements in some test cases to reduce the probability of spurious failures due to poor real-time performance of the test suite.

Fixes #88 Fixes #89 Fixes #90

[coveralls]

Pull Request Test Coverage Report for Build 719

• 139 of 142 (97.89%) changed or added relevant lines in 8 files are covered.
• 354 unchanged lines in 35 files lost coverage.
• Overall coverage increased (+0.5%) to 86.225%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pyuavcan/transport/can/_identifier.py	44	45	97.78%
pyuavcan/dsdl/_serialized_representation/_deserializer.py	80	82	97.56%
<!--	Total:	139	142	97.89%	-->

Files with Coverage Reduction	New Missed Lines	%
.test_dsdl_generated/sirius_cyber_corp/PerformLinearLeastSquaresFit_1_0.py	1	90.98%
.test_dsdl_generated/uavcan/metatransport/can/ArbitrationID_0_1.py	1	88.76%
.test_dsdl_generated/uavcan/node/ExecuteCommand_1_0.py	1	91.39%
.test_dsdl_generated/uavcan/node/port/ID_1_0.py	1	88.76%
.test_dsdl_generated/uavcan/pnp/cluster/RequestVote_1_0.py	1	92.92%
.test_dsdl_generated/uavcan/pnp/NodeIDAllocationDataMTU8_0_1.py	1	86.32%
.test_dsdl_generated/uavcan/si/sample/duration/Scalar_1_0.py	1	83.33%
.test_dsdl_generated/uavcan/si/sample/energy/Scalar_1_0.py	1	83.33%
.test_dsdl_generated/uavcan/si/sample/volume/Scalar_1_0.py	1	83.33%
.test_dsdl_generated/uavcan/si/sample/volumetric_flow_rate/Scalar_1_0.py	1	83.33%
<!--	Total:	354		-->

Totals
Change from base Build 710:	0.5%
Covered Lines:	18368
Relevant Lines:	20556

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💛 - Coveralls

[thirtytwobits]

Shouldn't you also bump the version with this change?