This makes the code independent of other encoding options like -gnatWx, -Wx

As an alternative to GitHub PR #9

This change breaks the public API. This is necessary, as in TOML 1.0.0
and unlike for previous format versions, arrays can hold values of
heterogeneous types (for instance: [1, "foo", True]).

This subtle change breaks the semantics of the API we had so far, which
assumed that arrays could contain only homogeneous values (only
integers, or only booleans, or ...). In order to adapt to the new
semantics, this commit removes the constructor/accessors with this
assumption.

The RFC 3339 allows "t" as the date/time separator and "z" for the UTC
time zone instead of the "standard" upper case "T" and "Z". Fix the
parser to handle these as well.

This makes the testsuite compatible with BurntSushi's testcase format.

A testcase JSON data (tests/valid/string/escapes.json) contains a raw
delete control code (\x7f), which is invalid in YAML files. Decode JSON
and re-encode it in YAML instead of assuming that all JSON data is valid
according to the YAML format.

Fixes #8

Also remove the redundant -E flag for the testsuite.

For #7

Fixes #7

Because of the testsuite bug corrected when transitionning to Python3,
some testcase baselines were not correct. This commit fixes them.

In order to reduce noise in "test.yaml" files, allow the "Z" syntax for
"+00:00" timezones, and allow the omission of millisecond when it is
zero.

In Python, booleans are subtypes of integers: "isinstance(True, int)" is
true, so we need to check for booleans before checking for integers.

Also fix a very embarrassing bug: the JSON dump comparator never
complained about expected/actual discrepancies... So this commit also
reveals lots of errors in the testsuite. Upcoming commits will fix them.

... to ADA_TOML_BUILD_MODE. This is an attempt to avoid conflicts with
incompatible definitions of this scenario variables: depending on
projects, this variable may accept incompatible sets of values: "debug",
"dev", "DEBUG", "production", "PROD", "release", etc.