Make it easier to install linguaevalia

`go get` is not enough because then we'd miss the scripts from `bin/`.
Also, when using `go get` codemirror is missing.

go/linguaevalia/Makefile

all: lib/codemirror.js lib/codemirror.css
DESTDIR = $(HOME)/.local/bin
RUNNERS = $(wildcard bin/run-*)
all: deps
deps: lib/codemirror.js lib/codemirror.css
lib:
	mkdir lib
lib/codemirror.css: lib
	curl -o $@ http://codemirror.net/lib/codemirror.css
linguaevalia: *.go
	go build .
install: linguaevalia
	install -t $(DESTDIR) linguaevalia $(RUNNERS)
clean:
	rm -rf lib