using terminalextensions breaks plots with plotlyjs backend in 0.6

With TerminalExtensions, attempts to `plot(1:10)` with the plotlyjs backend result in
```
Error showing value of type Plots.Plot{Plots.PlotlyJSBackend}:
ERROR: MethodError: no method matching handle_new_from_data(::String)
The applicable method may be too new: running in world age 21869, while current world is 21889.
Closest candidates are:
handle_new_from_data(::AbstractString) at /Users/bromberger1/.julia/v0.6/Rsvg/src/calls.jl:69 (method too new to be called from this world context.)
handle_new_from_data(::AbstractString, ::Gtk.GLib.GError) at /Users/bromberger1/.julia/v0.6/Rsvg/src/calls.jl:61 (method too new to be called from this world context.)
```

When TerminalExtensions is not loaded via `~/.juliarc.jl`, plots work.

Reproduce the failure by loading TerminalExtensions through ~/.juliarc.jl, then running plot(1:10) with the plotlyjs backend. Compare that startup path with loading the package later and trace the reported Rsvg/calls.jl method error. Done means the plot renders successfully in both loading modes without the world-age error.

Written by the indexing model from the issue text.