Feature/allow inclusive enddates

[ThePenguin1140]

This PR introduces the addition of a inclusiveEndDates arguments for Gantt chart definitions.
Adding this argument will add 1 day to all the end dates, effectively treating them to be inclusive.

Relevant Issues:

• Make Gantt chart date inclusive #868

Tasks:

• write specs for inclusive end dates
• add inclusive end date functionality to ganttDb.js
• write specs for gantt.jison parser improvements
• add definitions to the gantt.jison parser for inclusive end dates

Example Usage:

gantt
      title Inclusive end dates (Manual date should end on 4th)
      dateFormat YYYY-MM-DD
      axisFormat %d
      inclusiveEndDates
      section Section1
         2 Days: 1, 2019-01-01,2d
         Manual Date: 2, 2019-01-01,2019-01-03

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[coveralls]

Pull Request Test Coverage Report for Build 804

• 50 of 70 (71.43%) changed or added relevant lines in 2 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.3%) to 53.156%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/diagrams/gantt/ganttDb.js	33	35	94.29%
src/diagrams/gantt/parser/gantt.js	17	35	48.57%

Files with Coverage Reduction	New Missed Lines	%
src/diagrams/gantt/ganttDb.js	1	70.46%
src/diagrams/gantt/parser/gantt.js	3	45.07%

Totals
Change from base Build 795:	0.3%
Covered Lines:	2365
Relevant Lines:	4410

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💛 - Coveralls

[knsv]

It would be good if the diagrams you added to index.html also are added as e2e tests under e2e. This will make sure this functionality is not broken at a later date.