Use urfave/cli package (peak#94)

Fixes peak#98
Fixes peak#97
Fixes peak#23

Breaking changes:
 - 's5cmd get' command is removed. We have 2 identical commands without a clear reasoning. s5cmd cp <src> . has the same result as s5cmd get <src>.
 - batch-rm command is removed. Users can run 's5cmd rm' with variadic arguments. Wildcards are accepted.
 - 's5cmd -f' became 's5cmd run'
 - All errors are written to stderr
 - 's5cmd ls s3://non-existent/object' returns 1 instead of 0. Related: peak#23
 - Exit code for errors changed from 127 to 1
 - 's5cmd cp s3://bucket/object local/directory/' now creates the missing local/directory/ instead of returning an error.

Co-authored-by: Onur Sonmez <[email protected]>

.travis.yml

@@ -5,6 +5,7 @@ go:
 
 before_install:
   - go get honnef.co/go/tools/cmd/staticcheck
+  - go get mvdan.cc/unparam
 
 before_script:
   # e2e tests expects 0755 as default folder modbits, however on travis VMs,

Makefile

@@ -4,16 +4,6 @@ default: all
 
 .PHONY: all
 all: clean build test check
-.PHONY: dist
-dist: generate all
-
-.PHONY: fmt
-fmt:
-	@find ${SRCDIR} ! -path "*/vendor/*" -type f -name '*.go' -exec gofmt -l -s -w {} \;
-
-.PHONY: generate
-generate:
-	@go generate ${SRCDIR}
 
 .PHONY: build
 build:
@@ -24,19 +14,23 @@ test:
 	@go test -mod=vendor ./...
 
 .PHONY: check
-check: vet staticcheck check-fmt
+check: vet staticcheck unparam check-fmt
 
 .PHONY: staticcheck
 staticcheck:
-	@staticcheck -checks 'inherit,-SA4009,-U1000' ./...
+	@staticcheck -checks 'inherit,-U1000' ./...
+
+.PHONY: unparam
+unparam:
+	@unparam ./...
 
 .PHONY: vet
 vet:
 	@go vet -mod=vendor ./...
 
 .PHONY: check-fmt
 check-fmt:
-	@sh -c 'unfmt_files="$$(go fmt ./...)"; if [ -n "$$unfmt_files"  ]; then echo "$$unfmt_files"; echo "Go code is not formatted, run <make fmt>"; exit 1; fi'
+	@sh -c 'if [ -n "$(go fmt -mod=vendor ./...)" ]; then echo "Go code is not formatted"; exit 1; fi'
 
 .PHONY: clean
 clean: