Subject: [PATCH] Add LWS_LIBRARY_VERSION_NUMBER to lws_config.h.

Subject: [PATCH] Add LWS_LIBRARY_VERSION_NUMBER to lws_config.h.

This changeset adds a few preprocessor macros to lws_config.h to allow
a user of libwebsockets to determine at compile time which version of
lws they are compiling against.

This exposes the already existing LWS_LIBRARY_VERSION_MAJOR and _MINOR
values, and adds LWS_LIBRARY_VERSION_PATCH. This suggests that future
minor bugfix release versions of lws would be e.g. 1.6.0 -> 1.6.1 rather
than the style used previously: 1.2 -> 1.21.

The way this is currently set up means new minor revisions (with
_PATCH==0) always end with .0 but I could change this if preferred.

The most important addition is LWS_LIBRARY_VERSION_NUMBER, which
produces a number of the form 1005001 for version 1.5.1 - i.e. each part
major, minor, patch can extend from 0-999. This macro allows a very easy
compile time comparison of version numbers.