lib,src: report write errors

Propagate fopen() and fclose() errors to the callback if one is present.

Refs: #54

package: upgrade to newer nan version

People building against Node.js v12.x may encounter build errors with
heapdump when another dependency pins NAN to an outdated version.

Refs: #129

src: make compatible with node.js v12.x

Replace a removed V8 API with its NAN equivalent.

Fixes: #127

lib: fix heapdump write error reporting

The cleanup in the previous commit now makes it straightforward to fix.

Fixes: #125

src: fix include_dirs stanza on windows

It was reported that v0.3.10 fails to build on Windows because it can't
find nan.h. Change the include_dirs stanza to what node-iconv uses since
that one is known to work.

Fixes: #122

src: node 11 compatibility, switch to nan

* remove the compatibility shim, broken with node 11

* add a dependency on nan and switch the code base to it

* bump the patchlevel; bug fix only, no functional changes

Fixes: #121

Re-publish because of npm brain damage.

It looks like `npm publish` when `ignore-scripts=true` is set in .npmrc
creates a package that doesn't invoke `node-gyp rebuild` when installed;
the `scripts` property in the generated package.json is empty where it
normally inserts an auto-generated `{"install":"node-gyp rebuild"}`
stanza.

Fixes: #98
Refs: npm/npm#16243

lib: don't swallow module mismatch exceptions

Only try the debug build when the release build failed to load with
a MODULE_NOT_FOUND exception, otherwise we swallow module version
mismatch exceptions.

src: update compatibility shim

Update the compatibility shim to the latest version from
https://github.com/strongloop/strong-agent

Makes node-heapdump compatible with io.js v3.0.0.

Fixes #61.

src: disable win_delay_load_hook in binding.gyp

Fix a Windows-only load time linker error caused by nodejs/node@efadffe
("win,node-gyp: optionally allow node.exe/iojs.exe to be renamed"),
which was made the default in io.js v2.2.0.

Fixes the following error whe trying to load the add-on:

    LINK : fatal error LNK1194: cannot delay-load "iojs.exe" due to
    import of data symbol ""__declspec(dllimpo rt) const
    v8::OutputStream::`vftable'" (__imp_??_7OutputStream@v8@@6b@)";
    link without /DELAYLOAD:iojs.exe

Fixes #57.