Added a man page for Julia, mostly taken from pre-existing sources of documentation, and also modified the Makefile to build it.
Merge pull request #3354 from nabilhassein/manpage

WIP: man page
Redesign FD/File watchers

Fixes #3015
Fixes #3016
Fixes #3020
small improvement to gc parameters for #3441
Merge branch 'master' of github.com:JuliaLang/julia
src/gc.c: use if to define gc_push_root; clang doesn't like && here.

This definition was causing a lot of unused expressions warnings in
clang. Using an if statement quells them.
fix #2390
fixes for 7310f557aa9016693da6deac9915eaedea660e71 on windows
doc: use submodule for JuliaDoc instead of package

The JuliaDoc package seems to be giving some people trouble due to
pip being unavailable, so pull it in as a submodule instead.
Merge branch 'topic/doc-submodule'
allow macros to expand to nothing inside type blocks. fixes #3445
pkg2 wip: package caching works; install, update and remove in progress.
Merge branch 'master' of github.com:JuliaLang/julia
pkg2 wip: resolve now basically works.
Git: dir keyword allows working on repos without cd'ing into them.
pkg2: use Git API dir keyword instead of cding all the time.
pkg2: rollback on resolve failure, better handling of unknown packages.
Implemented @fetch and @fetchfrom, the fetch versions of @spawn and @spawnat
Fix #3448
tunnel option supports sshflags