libbuxton: Fix bug in hashmap freeing that can cause a segfault

When the client connection is closed, the hashmap is freed, but the
pointer to it was not set to null. Then when a new connection is made,
the key_hash pointer was checked if it points to null before trying
to access the hashmap. This caused a segfault when trying to
dereference the function pointer for the hash function, so it's now
being set to NULL to be able to test whether it was freed.
Simplifying public Buxton API

BuxtonSimple is an API that allows users who are new to Buxton or
familiar with vconf to utilize Buxton. There are fewer function
arguments for each function.  This is possibile because there are
default call back functions and a global client and fd provided in
the library. There are also newer functions similar to those found
in the vconf API (such has set_int32). The opening of the client
connection is embedded into each function called so the programmer
does not have to call buxton_open().
Buxton Simple

Added getters and modified setters to take in fewer arguments.
Added structures to get values and status to enable setting errno.
Errno now can be checked by the programmer when getting/setting a value.
New function buxtond_set_group, changes the group and creates it.
Created universal callback functions for set_value and get_value
for BuxtonDataTypes.

Added in test file lbuxton-simp_test.c separate from library
lbuxton-simp.c.
Add client disconnects to simple library functions

Added client_disconnect(), sbuxton_close() to lbuxton-simp.c
Added client_disconnect calls to simple library functions for getting
and setting. Fixed errors in Makefile.am, and fixed a bug in lbuxton.c,
where a freed Hashmap was not reset to Null, causing a segfault.
Added a missed client_disconnect() call

Added client_disconnect() to buxtond_set_group because it was missed
in the last commit.
    Separated bs_cb function into two

    bs_cb checks buxton_response_status(response).
    bs_print prints the debug message.
    buxton_debug will need to be used in place of printf statements.
    Must specify path to log.h in #include "../shared/log.h"
    Working towards removing all warning messages at compile time.
    Switch statements should handle BuxtonDataType MAX and MIN.
Separated test function from library function, made header file.

Main is now the only function in lbuxton-simp_test.c, and there is no
main in lbuxton-simp.c. There is now a header file lbuxton-simp.h
with the function prototypes for the library functions. The typedef
vstatus is also in the header and removed from lbuxton-simp.c.
This header in included in lbuxton-simp.c and lbuxton-simp_test.c.
Created libbuxtonsimp library

Added lines to Makefile.am to create the libbuxtonsimp library
(libbuxtonsimp.la). modified libbuxton-simp.pc.in, lbuxton-simp.h,
lbuxton-simp.sym, and lbuxton-simp_test.c with the correct values
for creating the library. In src/libbuxton-simp/ lbuxton-simp_test.c
can now be compiled with "gcc -g lbuxton-simp_test.c -lbuxtonsimp"
Changed header file name and location

Moved lbuxton-simp.h to src/include directory and renamed to buxton-simp.h
Changed the name from lbuxton-simp.h to buxton-simp.h in test file and library file
Modified the path to buxton-simp.h in Makefile.am after changing name
Deleted old buxton simple library header

Deleted lbuxton-simp.h
Added Header file for Buxton Simple API

Added buxton-simp.h to /src/include
Fixed warnings in simple API

Fixed warnings in lbuxton-simp.c and buxton-simp.h. Changed union
in vstatus to be named, added default case in switches, fixed a casting
error, and fixed return values.
Added Comments to Header File

TODO: remove internal library functions.
TODO: remove functions that are not used from header and lbuxton-simp.c
Created man pages for get, buxton-simp-api
Added demonstration code to get man page

Cleaned up the test code in lbuxton-simp_test.c, copied it into the
Code Example section in the buxtond_get man page. Added a forgotten
buxtond_get function.
Modified Makefile.am to install new man pages

Added a forgottan get man page. Added new man pages to Makefile.am
TODO: add set man pages to Makefile.am when they are finished
Fixed misspellings
Small corrections to man pages
Removed unneeded functions from lbuxton-simp.c

Remove unneeded functions - include all type-specific callbacks and
one create_group function and one remove group function. The callbacks
are replaced by one callback with a switch that handles all data
types. Renamed buxtond_remove_group2 to buxtond_remove_group for
simplicity. All changes are reflected in buxton-simp.h, lbuxton-simp.sym,
and lbuxton-simp_test.c
TODO: replace man page sample code with updated function name
Buxton Simple API Man Page For Setting Values

Added man page for buxtond_set_int32, buxtond_set_string, buxtond_set_uint32,
buxtond_set_int64, buxtond_set_uint64, buxtond_set_double, buxtond_set_float,
and buxtond_set_bool.

Slight modification to SEE ALSO section of buxtond_get_int32.3
Brushed up buxton-simp-api man page
Changed buxtond_remove_group2 to buxtond_remove_group