Resolve "Align SDE grammar to new timed features"

Closes #37

See merge request ESProjects/SDE!60

Resolve "Allow slash char in the contract name"

Closes #59

See merge request ESProjects/SDE!61

add unit test

Resolve "Fix maven build for Eclipse 2020-06 and Java8"

Closes #58

See merge request ESProjects/SDE!59

update README

Resolve "OSS formatter could be improved for contract refinements"

Closes #57

See merge request ESProjects/SDE!58

Resolve "Add LTL bounded in ocra grammar"

Closes #56

See merge request ESProjects/SDE!57

update profiles for Neon, 2020-06 and 2021-06

add `inf` value to InfiniteLiteral
add PI Literal to grammar
add temporal operators `X~` and `Y~` to grammar