Problem: undocumented limit on IPC paths in Linux is 107 chars

Solution: document the limit of 113 chars including ipc://. We might
fix this in libzmq by shortening an over-long IPC pathname into a
unique string; so long as this is done consistently in bind and in
connect, it will save applications from weird failures when they
use external data to generate IPC pathnames.
Merge pull request #1176 from hintjens/master

Problem: undocumented limit on IPC paths in Linux is 107 chars
Code cleanup
Merge pull request #1177 from hurtonm/master

Code cleanup
Update nuget package
Merge pull request #1178 from evoskuil/master

Update nuget package.
Stop session's timer when pipe terminates
Merge pull request #1179 from hurtonm/master

Stop session's timer when pipe terminates
Fix non-constant-expression narrowing

For OS X, the microseconds field is implemented as an int type. The implicit narrowing in the initializer list throws a compiler error for some compilers with C++11 support turned on. The specific error message is: "error: non-constant-expression cannot be narrowed from type 'long' to '__darwin_suseconds_t' (aka 'int') in initializer list [-Wc++11-narrowing]".

Tested on Clang 5.1.0 and Mac OS X 10.9.4.
Merge pull request #1181 from whoshuu/patch-1

Fix non-constant-expression narrowing
Fix hang terminating PGM ZMQ_SUB (#822).