preliminary toolchains documentation/spec
scanning using new toolchain layout (and related docs)
simpler tool execution schemes - only run installed programs from the PATH
more toolchain run examples
mention bash completion in readme
add header to `src tools` output
simpler layout of tools (no more toolchains)
move tools and ops subcmds under info
MAKE doc
add FAQ
basic scanning
scan using tools
elaborate on answer to "why are there 2 different execution schemes?"
rm old test
add back submodules (will extract into language tool repositories later)
fix refs to srcgraph tool
clarify tools doc
fix Markdown formatting
store everything in the SRCLIBPATH
Change protocol from git to https in .gitsubmodule

This fixes an issue where Travis CI builds would fail with error
'The command "git submodule update" failed.'