Peter M. Groen / cxxopts

Fixes #101. Allows leading zeroes in the integer parser.

Fixes #86. Rename some variables so that the overly strict shadows warning
on GCC 4.9 is not triggered.

Fixes #83.

Adds an overload for positional arguments taking a
`std::initializer_list`. When using an `initializer_list` with one
argument, the function call is ambiguous matching both `std::string`
and `std::vector<std::string>`.

Fixes #84. Implicit values are not handled very well. For example:

    --foo false true
    --foo --bar

In the first, `false` is an argument to `--foo`, and then `true` is a
positional argument. In the second, because of the hyphen in `--bar`, `--foo`
is parsed with its implicit value. This seems inconsistent and unintuitive.

Better is that implicit values *never* consume the next parameter to be
completely consistent. This means that values with an implicit parameter
*must* be specified using the `--option=value` form.

add booleans into the changelog and the readme

This is far from ideal, but it's the first step in moving the parse
result to an immutable object so that the parser can be reused.