Update build instructions about ipe

[dimiro1]

@izimobil Which Golang version are you using?

[izimobil]

@dimiro1

$ go version
go version go1.11.4 linux/amd64

[dimiro1]

Try to clone the repo (https://github.com/dimiro1/ipe.git) on a directory outside your GOPATH and run go build

[izimobil]

$ pwd
/tmp/ipe
$ go build
go: finding github.com/gorilla/context v1.1.1
go: finding github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
go: finding github.com/gorilla/mux v1.6.2
go: finding github.com/pusher/pusher-http-go v1.3.0
go: finding github.com/davecgh/go-spew v1.1.1
go: finding github.com/gorilla/handlers v1.4.0
go: finding github.com/pmezard/go-difflib v1.0.0
go: finding github.com/stretchr/testify v1.2.2
go: finding golang.org/x/crypto v0.0.0-20181112202954-3d3f9f413869
go: finding gopkg.in/yaml.v2 v2.2.1
go: finding github.com/gorilla/websocket v1.4.0
go: finding gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405
go: downloading github.com/gorilla/mux v1.6.2
go: downloading github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
go: downloading gopkg.in/yaml.v2 v2.2.1
go: downloading github.com/gorilla/handlers v1.4.0
go: downloading github.com/gorilla/websocket v1.4.0

It just stop after that and no files are generated.

[dimiro1]

Right, then execute

cd cmd
go build -o ipe

[izimobil]

Yes ! it works, many thanks @dimiro1 !