Added `make dep` to root Makefile, added Development Environment setup

to README

Makefile

@@ -42,6 +42,9 @@ endif
 
 all: $(TARGET)
 
+dep:
+	$(MAKE) -C dep
+
 run: $(TARGET)
 ifeq ($(ARCH), lin)
 	LD_LIBRARY_PATH=dep/lib ./$<
@@ -165,4 +168,4 @@ distplugins:
 plugins:
 	for f in plugins/*; do (cd "$$f" && ${CMD}); done
 
-.PHONY: all run debug clean dist allplugins cleanplugins distplugins plugins
+.PHONY: all dep run debug clean dist allplugins cleanplugins distplugins plugins

README.md

@@ -4,22 +4,46 @@
 
 ![Rack screenshot](https://vcvrack.com/images/screenshot.png)
 
+This README includes instructions for building Rack from source. For information about the software, go to https://vcvrack.com/.
+
+## Setting up your development environment
+
+Rack's dependencies (GLEW, glfw, etc) do not need to be installed on your system, since specific versions are compiled locally during the build process. However, you need proper tools to build these dependencies.
+
+### Mac
+
+Install [Xcode](https://developer.apple.com/xcode/) or *command line developer tools* with `xcode-select --install`.
+Install [CMake](https://cmake.org/), preferably from [Homebrew](https://brew.sh/).
+
+If you would like MacOS 10.7+ users to be able to run your binaries and plugins, install the MacOS 10.7 SDK using the [xcodelegacy](https://github.com/devernay/xcodelegacy) script.
+
+### Windows
+
+Install [MSYS2](http://www.msys2.org/) and launch the mingw64 shell (not the default msys2 shell).
+Install build dependencies with the pacman package manger.
+
+	pacman -S git make tar unzip mingw-w64-x86_64-gcc mingw-w64-x86_64-cmake
+
+### Linux
+
+With your distro's package manager, make sure you have installed `gcc`, `make`, `cmake`, `tar`, and `unzip`.
+
 ## Building
 
 *If the build fails for you, please report the issue with a detailed error message to help the portability of Rack.*
 
 Clone this repository and `cd` into it.
-On Windows, use [MSYS2](http://www.msys2.org/) and launch a mingw64 shell.
 
 Clone submodules.
 
 	git submodule update --init --recursive
 
 Build dependencies locally.
+You may use make's `-j$(nproc)` flag to parallelize builds across all your CPU cores.
 
-	cd dep
-	make
-	cd ..
+	make dep
+
+You should see a message that all dependencies built successfully.
 
 Build Rack.