1070 Bare Brace map constructor syntax

[michaelhkay]

Makes the keyword "map" in map constructors optional.

Fix #1070

[ChristianGruen]

🔝

[ndw]

The CG agreed to merge this PR at meeting 071

[ChristianGruen]

Sorry for creating the conflicts; I hope it’s easy to fix.

Formatting of maps and arrays:

map { 1: "I", 2: map { "II": [ "III", "IV" ] } },
{ 1: "I", 2: { "II": [ "III", "IV" ] } }

For arrays, whitespace is used after [ and before ] to illustrate that the constructs are no predicates.

[michaelhkay]

I hve (a) resolved the conflicts, and (b) used the new syntax extensively in examples in the F+O and XSLT specs.