v3.3.0 (#525)

* feat: directory-scoped cheatpaths

`cheat` now searches for a `.cheat` directory in the current working
directory. If found, that directory is (temporarily) appended to the slice
of cheatpaths.

* makefile wip

* fix: appeases linter

Appeases linter (`go vet`) by adding quotation marks to YAML struct
tags.

* chore: modifies .gitignore

Adds `tag` to `.gitignore`

* feat: adds Makefile

Adds a `Makefile` for managing build-related tasks.

* chore: documents directory-local paths

Adds documentation regarding the new directory-local cheatpath
functionality.

* chore: updates dependencies

* chore: bumps version to 3.3.0

* chore: updates bin scripts

- Removes `build_release.sh`
- Places deprecation notice in `build_devel.sh`, as its purpose has been
  superceded by the `Makefile`.

Makefile

@@ -0,0 +1,133 @@
+# paths
+makefile := $(realpath $(lastword $(MAKEFILE_LIST)))
+root_dir := $(shell dirname $(makefile))
+cmd_dir  := $(root_dir)/cmd/cheat
+dist_dir := $(root_dir)/dist
+
+# executables
+CAT    := cat
+COLUMN := column
+CTAGS  := ctags
+GO     := go
+GREP   := grep
+LINT   := revive
+MKDIR  := mkdir -p
+RM     := rm
+SCC    := scc
+SED    := sed
+SORT   := sort
+
+# build flags
+BUILD_FLAGS  := -ldflags="-s -w" -mod vendor
+GOBIN        :=
+
+# NB: this is a  kludge to specify the desired build targets. This information
+# would "naturally" be best structured as an array of structs, but lacking that
+# capability, we're condensing that information into strings which we will
+# later split.
+#
+# Format: <architecture>/<os>/<arm-version>/<executable-name>
+.PHONY: $(RELEASES)
+RELEASES :=                               \
+	amd64/darwin/0/cheat-darwin-amd64       \
+	amd64/linux/0/cheat-linux-amd64         \
+	amd64/windows/0/cheat-windows-amd64.exe \
+	arm/linux/5/cheat-linux-arm5            \
+	arm/linux/6/cheat-linux-arm6            \
+	arm/linux/7/cheat-linux-arm7
+
+# macros to unpack the above
+parts = $(subst /, ,$@)
+arch  = $(word 1, $(parts))
+os    = $(word 2, $(parts))
+arm   = $(word 3, $(parts))
+bin   = $(word 4, $(parts))
+
+
+## build: builds an executable for your architecture
+.PHONY: build
+build: clean generate
+	$(GO) build $(BUILD_FLAGS) -o $(dist_dir)/cheat $(cmd_dir)
+
+## build-release: builds release executables
+.PHONY: build-release
+build-release: $(RELEASES)
+
+.PHONY: generate
+generate:
+	$(GO) generate $(cmd_dir)
+
+.PHONY: $(RELEASES)
+$(RELEASES): clean generate check
+ifeq ($(arch),arm)
+	GOARCH=$(arch) GOOS=$(os) GOARM=$(arm) $(GO) build $(BUILD_FLAGS) -o $(dist_dir)/$(bin) $(cmd_dir)
+else
+	GOARCH=$(arch) GOOS=$(os) $(GO) build $(BUILD_FLAGS) -o $(dist_dir)/$(bin) $(cmd_dir)
+endif
+
+## install: builds and installs cheat on your PATH
+.PHONY: install
+install:
+	$(GO) install $(BUILD_FLAGS) $(GOBIN) $(cmd_dir) 
+
+$(dist_dir):
+	$(MKDIR) $(dist_dir)
+
+## clean: removes compiled executables
+.PHONY: clean
+clean: $(dist_dir)
+	$(RM) -f $(dist_dir)/*
+
+## distclean: removes the tags file
+.PHONY: distclean
+distclean:
+	$(RM) $(root_dir)/tags
+
+## setup: installs revive (linter) and scc (sloc tool)
+.PHONY: setup
+setup:
+	GO111MODULE=off $(GO) get -u github.com/boyter/scc github.com/mgechev/revive
+
+## sloc: counts "semantic lines of code"
+.PHONY: sloc
+sloc:
+	$(SCC) --exclude-dir=vendor
+
+## tags: builds a tags file
+.PHONY: tags
+tags:
+	$(CTAGS) -R $(root_dir) --exclude=$(root_dir)/vendor
+
+## vendor: downloads, tidies, and verifies dependencies
+.PHONY: vendor
+vendor: lint # kludge: revive appears to complain if the vendor directory disappears while a lint is running
+	$(GO) mod vendor && $(GO) mod tidy && $(GO) mod verify
+
+## fmt: runs go fmt
+.PHONY: fmt
+fmt:
+	$(GO) fmt $(root_dir)/...
+
+## lint: lints go source files
+.PHONY: lint
+lint:
+	$(LINT) -exclude $(root_dir)/vendor/... $(root_dir)/...
+	$(GO) vet $(root_dir)/...
+
+## test: runs unit-tests
+.PHONY: test
+test: 
+	$(GO) test $(root_dir)/...
+
+## check: formats, lints, vendors, and run unit-tests
+.PHONY: check
+check: fmt lint vendor test
+
+## help: displays this help text
+.PHONY: help
+help:
+	@$(CAT) $(makefile) | \
+	$(SORT)             | \
+	$(GREP) "^##"       | \
+	$(SED) 's/## //g'   | \
+	$(COLUMN) -t -s ':'