Parser accepts key paths

[lebotlan]

What

The parser now accepts key paths (instead of single keys), e.g. k1.k2.k3 = 100

Why

It is part of the spec! (and can be occasionally useful)

How

The only modified code is in the parser: menhir_parser.mly

• grammar is extended to accept key paths
• functions that create tables now expect key paths instead of single keys. The path is split into a list of keys and the last key. The list of keys leads to the hashtable in which the last key will be inserted.

Testing

I added a couple of tests, in particular path_example1.toml and path_example2.toml which are expected to give the same TOML tree, although the input syntax is different.

Besides

I have replaced most of the $1 $2 in the parser by named variables, to avoid position-dependent parameters.