Initial wrapping for nng_stream (fixes #43) and iov (fixes #47)

[jeikabu]

• Building nng@HEAD
• Decouple NngSocket from NngAio and NngAio from NngCtx
  • Aio can be created without a socket
  • Aio creation is simpler and less error-prone
• Flesh out NngAio and working stream send/receive iov
• Use short get/set functions for options (see nng issue #901)

[codecov[bot]]

Codecov Report

Merging #50 into dev will increase coverage by 0.9%. The diff coverage is 94.88%.

@@            Coverage Diff            @@
##              dev      #50     +/-   ##
=========================================
+ Coverage   91.84%   92.74%   +0.9%     
=========================================
  Files          40       45      +5     
  Lines        1765     2067    +302     
=========================================
+ Hits         1621     1917    +296     
- Misses        144      150      +6

Impacted Files	Coverage Δ
runng/src/protocol/pull0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/pair1.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/sub0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/push0.rs	100% <ø> (ø)	:arrow_up:
runng/src/options.rs	100% <ø> (+10.52%)	:arrow_up:
runng/src/protocol/pub0.rs	100% <ø> (ø)	:arrow_up:
runng/src/lib.rs	83.33% <ø> (-5.56%)	:arrow_down:
runng/src/factory.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/req0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/rep0.rs	100% <ø> (ø)	:arrow_up:
... and 47 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 99b62c2...8dc8e64. Read the comment docs.

[codecov[bot]]

Codecov Report

Merging #50 into dev will increase coverage by 0.9%. The diff coverage is 94.88%.

@@            Coverage Diff            @@
##              dev      #50     +/-   ##
=========================================
+ Coverage   91.84%   92.74%   +0.9%     
=========================================
  Files          40       45      +5     
  Lines        1765     2067    +302     
=========================================
+ Hits         1621     1917    +296     
- Misses        144      150      +6

Impacted Files	Coverage Δ
runng/src/protocol/pull0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/pair1.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/sub0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/push0.rs	100% <ø> (ø)	:arrow_up:
runng/src/options.rs	100% <ø> (+10.52%)	:arrow_up:
runng/src/protocol/pub0.rs	100% <ø> (ø)	:arrow_up:
runng/src/lib.rs	83.33% <ø> (-5.56%)	:arrow_down:
runng/src/factory.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/req0.rs	100% <ø> (ø)	:arrow_up:
runng/src/protocol/rep0.rs	100% <ø> (ø)	:arrow_up:
... and 47 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 99b62c2...211befa. Read the comment docs.