* compiler: rename vget to tools/vpm, implement draft support for v vpm search, v vpm update, v vpm install, v vpm remove, v vpm help .
* compiler: use "v pm" instead of "v vpm" to reduce the redundancy of typing, as suggested by slapden
* Use 'v install modulename', 'v search keywords', 'v update modulename', 'v remove modulename' instead of the longer 'v pm install modulename' etc.
* Move compiler/ under vlib/compiler/ .
* Add a minimal compiler/main.v driver program.
* Cleanup compiler/main.v .
* Make most compiler tests pass again.
* Apply the fix by @joe-conigliaro , so that the rest of the compiler tests are fixed too.
* Thanks to @avitkauskas, now the vlib/vcompiler/tests/str_gen_test.v test does not need to be special cased anymore.
* Reapply @joe-conigliaro fix for vgen.