Start work on multi-instance ImGui

Update imgui (new .gitignore)

Actually, for dev builds, we *do* need by default SystemJS modules

imgui-js needs to be imported as an ambient module from imgui_impl in order for typescript to not think that it's a separate module, and giving all globals (like bind) a suffix (bind$1)

Attempt to just use commonjs modules so we can import from elsewhere with rollup

Bring imgui to a local fork, and ignore some files

The imgui renderer layer for the examples needs to take the devicePixelRatio into account when calculating pointer offset coordinates. Fixes #14

Merge pull request #13 from richardlalancette/master ...

Improve instructions

only check for canvas rendering contexts in browsers

Improve instructions

a modularized emscripten module does not return a promise

update dependencies

rebuild dist

limited CanvasRenderingContext2D rendering

clamped array for texture data

access memory buffer through heap

rebuild

move drag/drop payload data into script

check for clipboard event data

update dependencies

Emscripten 1.38.28

update dependencies; rebuild

v1.67

Emscripten 1.38.23

disable IM_ASSERT

SystemJS 0.21.6

Emscripten 1.38.21

dist

v1.66

Emscripten 1.38.20