Fixes #85

Ensures callback always executes even for zero-len files.

Fixes #90

Conflicts:
	NEWS

(cherry picked from commit d7def60c4784fed39fc8714753304a150da131c7)

Conflicts:
	setup.py

(cherry picked from commit 3709d2e02bf67ccc272e1f2311e5db125a922ba0)

(cherry picked from commit c27915d55182cfa22c517c2d6d887316fc89c80a)

(cherry picked from commit 4cb9fed74bbde4730d2901dde4adb7cb47ae796a)

(cherry picked from commit d516fe71ea1d8bdb7b2e278fa519f7f860d7e234)

(cherry picked from commit 734f3d6f42ef1564f473fee5526e0354fc8196fc)

Conflicts:
	test.py

(cherry picked from commit baa930eb583b65938cfcfa272a1eb2af12df3502)

(cherry picked from commit c8e76e3a801098ecfec02fe52cd83bb7fab9f19a)

Fixes #11
(cherry picked from commit 01ab79211c3aeeb8dd55dafff3ce7b3a77844ca6)

(cherry picked from commit 351bdb72e539c373985e108c89f61839f3acdd2a)

Conflicts:
	paramiko/agent.py
	paramiko/client.py
	paramiko/transport.py

(cherry picked from commit 503d7e62602cfe3ed63a4f44fba12874a17aa199)

(cherry picked from commit abfefc2f95c377cc134d9b0b71c8cdd692f321c8)

Conflicts:
	setup.py

(cherry picked from commit 5b8cdd990fea9269f8b5297ad1e3e52de08f2ee6)

- explicit check for ['password'] as remaining auth type
(cherry picked from commit 53a3421da6d74333c4679fd6289d418917833b44)

(cherry picked from commit 0a4aa8a9d119022adef3b8d89f129ea26110fc1a)

(cherry picked from commit be19c273bbe77d58fd67edeabf344ff253997b23)

(cherry picked from commit 8793771f3804b3f9bb4bf63d0b36ca105de78979)

(cherry picked from commit 2f4303df3e7477dca28badee2f1cc14573befab6)

(cherry picked from commit a753df8ea43c26114942147fde2f10f82da5ca29)

(cherry picked from commit 803820c3c8b1aaf2a11588431582916dbb23ea1e)