Peter M. Groen / cxxopts

* Fixes #240: Multiple long option names / aliases

* We now use a vector of long option names instead of a single name
* When specifying an option, you can provide multiple names separated by commas, at most one of which may have a length of 1 (not necessarily the first specified name). The length-1 name is the single-hyphen switch (the "short name").
* Hashing uses the first long name
* Option help currently only uses the first long name.

* Fixes #345, fixes #346, regards #340: Put exceptions in a sub-namespace and renamed them accordingly.

* Also fixed some "loose ends" regarding namespace indentation which were missing in PR #350.

* Dropped `required_option_missing` as it is unused.

Memory leak was caused by `exit`.

Ref #242. Adds an example in the example file showing the unmatched
arguments that are stored.

* Add iterator (#126) and easily print-out (#223) to ParseResult

`cxxopts` doesn't modify the contents of the argv strings. This changes
the parse function to take a reference to a `const char**`.

Fixes #219. The example was wrong as ParseResult can't be returned out
of scope of the options parser.

Fixes #201. Parse char type correctly and check for length.

Improve parsing into std::vector so that a single argument can take a list.

Fixes #132. Since the map of options is shared between Options and
ParseResult, they should use a shared pointer instead of a reference so
that ParseResult can be returned without referencing destroyed memory.

Allows unrecognised options to be left alone by the parser without throwing an exception.

This reverts commit 0f819a5cabb611ada4c41a5208c6bf1178f804be.

* Added const to argv type for better interoperability.

Fixes #102. Don't show the default value when it is a boolean and the
value is false. Note that this is a bit of a hack and the
implementation should probably be reevaluated in the future.

Fixes #72. This adds an option for positional arguments to be
shown in the help output.

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.

Adds generic parsing of types using `operator>>`, in particular allows
parsing of floats and doubles.

Fixes #57.

Allows spaces after the comma between the short and long option
specification.

Conflicts:
	src/cxxopts.hpp
	src/example.cpp

Conflicts:
	src/cxxopts.hpp