Intermediate Representation (IR) Support

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Completely new package, Intermediate Representation, designed to bring sanity to the AST by providing contract visual representation that is readable.

Current version will not support function body statements, except FunctionCall.

Function call will be used later on to build control flow graphs so we'll add it inside.

Following package will be used so we can properly build ABIs as well as future CFG graphs (Control Flow Unit) 🥳

Each node has AST node connected to it so in case that any additional transformations/retrievals are needed such as source location, body statements, etc... can be done manually. In the future full support for statements will come but for now, building only necessary parts.

There's one primary unit test in builder_test.go that does most of the required job. Rest of the unit tests are just boilerplates for the future and to test out that getters are actually there, in place, working.

Bugfixes:

• Reference forward declaration were broken for: Source Unit, BaseContracts, Imports and Symbols. Basically, everywhere in cases where contract sources are randomized. This is now resolved and we're one step closer to the fully correctly referenced ast.
• Some of the nodes didn't use pointer, I've made sure it's sorted out.
• Fallback and Revert had Declaration in name which I've dropped to be in standard as everything else.

Additions:

• Added support for MaskLocalSourcesPath in sources.go ensuring returned response path do not contain full path. This is for example when we're serving it from the browser to not see local full path where it's located 😂

[coveralls]

Pull Request Test Coverage Report for Build 5789356876

• 1734 of 2357 (73.57%) changed or added relevant lines in 53 files are covered.
• 9 unchanged lines in 5 files lost coverage.
• Overall coverage decreased (-0.7%) to 79.122%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ast/parameter_list.go	6	7	85.71%
ast/if.go	5	7	71.43%
ir/event.go	52	55	94.55%
ir/modifier.go	23	26	88.46%
ir/parameter.go	26	29	89.66%
ir/pragma.go	35	38	92.11%
ast/primary_expression.go	20	25	80.0%
ir/root.go	68	73	93.15%
ast/builder.go	0	6	0.0%
ast/state_variable.go	4	10	40.0%

Files with Coverage Reduction	New Missed Lines	%
ast/function_call.go	1	86.05%
ast/if.go	1	86.3%
ast/parameter_list.go	1	85.87%
ast/primary_expression.go	3	89.16%
ast/tuple.go	3	91.59%

Totals
Change from base Build 5767250455:	-0.7%
Covered Lines:	8277
Relevant Lines:	10461

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💛 - Coveralls

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At this point we have all of the basic parts covered from the AST besides the FunctionCall.

Prior this PR is merged to master following needs to happen:

• FunctionCall needs to be implemented.
• Protocol buffers needs to be resolved.
• Unit tests! Not going out without it!

Once this is done, we're ready for release of 1st revision of the Intermediate Response package!