Use CMake module GNUInstallDirs to support platform-specific installation directories

* Enable Matlab by default

* Cleanup CMakeLists.txt

Update tests

Fails randomly on msvc

Readme

* cmake: set default Release build type

* cmake: optionally enable cxx

* cmake: enable bindings with static library

* cmake: build testopt

* cmake: enable cxx for python bindings

* cmake: install nlopt.pc

* cmake: added missing compiler checks

* cmake: add octave support

* cmake: add guile bindings

* cmake: provide package_source target

* cmake: generate api headers

* Add Appveyor config file

* Test MinGW build

* Removed autotools

* cmake: install man

* re-implement getopt for test

* travis: +osx

* cmake: man/pkgconfig unix only

* add only Python test if built

* cmake: pkgconfig on mingw

* Fix octave include

* Find numpy includes

* Detect SWIG at top-level

* cmake: RPATH policy

* appveyor: shared build

* Add cmake config files

* travis: shared builds

* appveyor: no shared builds

* BUILD-MINGWXX.sh are superseeded by toolchain files

octave: Tell Git to ignore `dummy` build output

also link with GUILE_LIBS

Chain build rules for guile and python bindings to avoid race conditions in parallel builds

add missing linking for C++

Fixes memory leak in auglag/auglag.c

Fixes a memory leak in auglag/auglag.c where the working space xcur wasn't being `free`d under certain conditions.

fix nlopt.pc with cxx enabled

Add Travis script

simplify python test

fix conversion error in stop.c

hi,

I got this error when compiling git head with gcc:

```
make[2]: Entering directory '/home/schueller/projects/nlopt/build/util'
/bin/sh ../libtool  --tag=CC   --mode=compile g++ -DHAVE_CONFIG_H -I. -I../../util -I..  -I../../api   -g -O2 -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align -Wno-long-long -pedantic -Wshadow -Wwrite-strings -Wredundant-decls -Wundef -Wconversion -MT stop.lo -MD -MP -MF .deps/stop.Tpo -c -o stop.lo ../../util/stop.c
libtool: compile:  g++ -DHAVE_CONFIG_H -I. -I../../util -I.. -I../../api -g -O2 -Wall -W -Wcast-qual -Wpointer-arith -Wcast-align -Wno-long-long -pedantic -Wshadow -Wwrite-strings -Wredundant-decls -Wundef -Wconversion -MT stop.lo -MD -MP -MF .deps/stop.Tpo -c ../../util/stop.c  -fPIC -DPIC -o .libs/stop.o
../../util/stop.c: In function ‘char* nlopt_vsprintf(char*, const char*, __va_list_tag*)’:
../../util/stop.c:151:20: error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]
         p = realloc(p, len);
                    ^
Makefile:426: recipe for target 'stop.lo' failed
```

Use octave_map

add nlopt_get_errmsg(opt) for more informative error messages; automatically used in C++ and Python exceptions