Conf command macros
-------------------

The build script generates a large number of macros for reducing the code required for command
definitions.

There are basically three types of macros :

- combination bitmasks

    e.g. NDK_HTTP_MAIN_SRV_CONF  =  (NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF)

- base command structures

    e.g. NDK_HTTP_MAIN_CONF_TAKE1

- conf-set command structures

    e.g. NDK_HTTP_CONF_STR


Combination bitmasks
--------------------

Basically combinations of existing bitmasks for locations, with general > specific order

NDK_HTTP_CONF = (NGX_HTTP_MAIN_CONF | NGX_HTTP_SVR_CONF | NGX_HTTP_SIF_CONF | NGX_HTTP_LOC_CONF | NGX_HTTP_LIF_CONF)


Base command structures
-----------------------

These macros are basically there as wrappers for the conf-set command structures, and but incorporate 
the bitmask element into the name of the macro.


Conf-set command structures
---------------------------

These macros simplify creating commands that use any of the build-in conf-set functions or any of those
added by the NDK.

e.g.  NGX_HTTP_MAIN_SRV_STR ("name", prop, NULL)

where prop is the name of the property that is a ngx_str_t.  Whether this is in the loc conf, main conf
or svr conf is generated automatically in by the macro.

NOTE : you need to set the following if they will be used (using macro definitions) :

ndk_module_main_conf_t
ndk_module_srv_conf_t
ndk_module_loc_conf_t

e.g

#define     ndk_module_loc_conf_t       ngx_http_my_module_loc_conf_t


TODO
----
Much better documentation for this