Should continue if process has no file handles left
Fixed response to file handle exhaustion

- libzmq no longer asserts when file handles are exhausted
- so all classes that create sockets have to be robust against this
- they return NULL on construction
Fixed zproxy to deal with socket exhausted errors

- also fixed zproxy_bind to return 0 on OK, -1 on errors
Merge pull request #293 from hintjens/master

Fixed response to file handle exhaustion
Add an "add" function for zpoller.

Added a function to add a reader after the initial poller has been
created. I'm not sure how correct this patch is but it passes the self
test. I figured that because both the use case and the patch still
conforms to the zpoller description that it'll be okay.

Also can I get discussion on the documentation and function name for
this?

Use Case:
Creating sockets in a loop and adding them to a poller after it's been
created.

Limitations:
  * Appends a reader so it'll have the lowest priority.
  * There's no corresponding remove function.

Signed-off-by: Shannen Saez <shannenlaptop@gmail.com>
Merge pull request #298 from shancat/feature/poller_add

Add an "add" function for zpoller.
Docs seem to be out of date so update them.

I did this by running this:
```
./autogen.sh
./configure
cd doc
make
```

Signed-off-by: Shannen Saez <shannenlaptop@gmail.com>
Merge pull request #300 from shancat/feature/doc_update

Docs seem to be out of date so update them.
Remove empty README file.

It's confusing enough that there is three different README files. Now
it's only two thirds as confusing.

Signed-off-by: Shannen Saez <shannenlaptop@gmail.com>
libsodium is no longer broken.

Just checkout libsodium master because it no longer breaks the build.

Signed-off-by: Shannen Saez <shannenlaptop@gmail.com>
Merge pull request #301 from shancat/feature/travis-libsodium

libsodium is no longer broken.
fixes to be compilable by mingw32

with -Werror
Ctrl-C handler for Windows
Merge pull request #302 from pijyoi/win32_ctrlc

Ctrl-C handler for Windows
Fixed to make work with ZMQ v3.2
Extending Travis CI build to ZMQ 3.2
Extending Travis CI build to ZMQ 3.2
Disabled zmonitor for libzmq v3.2

- current code assumes libzmq v4.x
- whole class and interface is null now when built on libzmq < v4
Fixed zpoller for ZMQ v2
Added zcert_meta_keys method

This gives the caller a list of all the keys in the metadata.