Allow multiple --ens-api flags to be specified with value format
[tld:][contract-addr@]url.

Backward compatibility with only one --ens-api flag and --ens-addr
flag is preserved and conflict cases are handled:

 - multiple --ens-api with --ens-addr returns an error

 - single --ens-api with contract address and --ens-addr with
   different contract address returns an error

Previously implemented --ens-endpoint is removed. Its functionality
is replaced with multiple --ens-api flags.

Implement a CLI flag that can be repeated to allow multiple ENS
resolvers for different TLDs.

it's -> its

pet peeve, and I like to imagine I'm not alone.

core/bloombits: handle non 8-bit boundary section matches

core/vm: improve jumpdest analysis

core: split same-td blocks on block height

* cmd, dashboard: dashboard using React, Material-UI, Recharts

* cmd, dashboard, metrics: initial proof of concept dashboard

* dashboard: delete blobs

* dashboard: gofmt -s -w .

* dashboard: minor text and code polishes

* accounts, internal: return an error if no suitable estimated gas found

* accounts, internal: minor polishes on the gas estimator

core/vm: fix typos in jump_table.go

Dockerfile: support alltools image beside plain Geth

vendor: add github.com/stretchr/testify test dependency

dockerignore, internal/build: forward correct git folder

* cmd/puppeth: handle encrypted ssh keys

* cmd/puppeth: fix unconvert linter error

* .dockerignore, internal/build: Read git information directly from file

This commit changes the way of retrieving git commit and branch for build
environment from running git command to reading git files directly.

This commit also adds required git files into Docker build context.

fixes: #15346

* .dockerignore: workaround for including some files in .git

github.com/stretchr/testify is a useful library for doing
assertion in tests. It makes assertions in test more less verbose and
more comfortable to read and use.

* build: enable unconvert linter

 - fixes #15453
 - update code base for failing cases

* cmd/puppeth: replace syscall.Stdin with os.Stdin.Fd() for unconvert linter

Fixes #15373

This changes behaviour: before if the owner/amount didn't match, it
resulted in a successful execution without doing anything; now it
results in a failed execution using the revert opcode (remainder gas
is not consumed).

build: enable gofmt and misspell linters

travis: bump Android NDK version and Android Go builder

* build: [finishes #15372] implements generalized linter and travis job

* .travis, build: minor polishes, disable deadcode

All logs in the FilterLog return value would be the same object 
because the for loop captured the pointer to the iteration variable.