cmd/gop: update build & install command

[visualfc]

1. gop build [-v] [-o output] <gopSrcDir|gopSrcFile>

   generate gop_autogen.go to source dir

gop build   // set build source dir is $PWD,  same `gop build . `
gop build file.gop  // target name set $PWD/fileName[.exe]
gop build dir //target name set $PWD/dirName
gop build -o output // target name set output

2. gop install [-v] <gopSrcDir|gopSrcFile>

   generate gop_autogen.go to source dir

gop install   // set build source dir is $PWD,  same `gop install .`
gop install dir // use go install and set GOBIN=GOPBIN
gop install file.go // use go build -o $GOPBIN/fileName[.exe]

[codecov-io]

Codecov Report

Merging #623 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #623   +/-   ##
=======================================
  Coverage   89.86%   89.86%           
=======================================
  Files          42       42           
  Lines        9163     9163           
=======================================
  Hits         8234     8234           
  Misses        656      656           
  Partials      273      273           

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