Mass bind -> lambda conversion

See merge request count0/graph-tool!30

Source file work done with custom-modified versions of clang-format
and clang-tidy, via the modernize-avoid-bind checker. Headers were
modified by hand. A script removed uses of <functional> and <boost/bind.hpp>.

This implements buffered io, instead of loading the entire edge list to memory.

Allow graph_tool.draw.draw_hierarchy to be used without GTK installed

See merge request count0/graph-tool!29