Dvc

* Fix build issues.

* test: scm: convert to dir helpers (3116) efiop
* get: refactor handling of git files and git-only repos (3114) efiop
* test: get_url: convert to dir helpers (3115) efiop
* test: init: convert to dir helpers (3117) efiop
* tests: external_repo: convert to dir helpers (3118) efiop
* add space for import help text (3126) pared
* test: refactor ssh related functions in test helper classes (3123) skshetry
* summon: fixes and dvcx prereq (3101) Suor
* gdrive: add support for teamDriveId (3016) efiop
* rwlock: flush and fsync (3076) efiop
* get: handle non-DVC repositories (3097) fabiosantoscode
* run: tests: migrate to dir helpers (3094) pared
* state: tests: migrate to dir helpers (3096) pared
* update: tests: migrate to dir helpers (3100) pared
* stage: tests: migrate to dir helpers (3099) pared
* tests: remove redundant native ssh tests (3104) efiop
* py3: use links from os module (3090) mroutis
* repro: tests: migrate to dir helpers (3091) pared
* dvc: optimize Git.is_tracked() (3053) Suor
* Move fs utilities to fs.py from __init__.py (3093) algomaster99
* import url: test: migrate to dir helpers (3072) pared
* output: tests: migrate to dir helpers (3083) pared
* py3: remove code related to py2 limitations (3034) mroutis
* remote: test: migrate to dir helpers (3086) pared
* pipeline: test: migrate to dir helpers (3085) pared
* install: tests: migrate to dir helpers (3074) pared
* setup: get rid of py2 reqs (3082) efiop
* py3: use format_exc instead of print_exception (3078) mroutis
* rwlock: check that .dvc/lock is locked (3075) efiop
* ui: warn about ignored options for `dvc status` and a grammar fix (3027) Suor
* ui: don't show exception for "Too many files" error (3058) efiop
* Write test for `walk_files` to check if it accepts Path-like and str objects (3035) algomaster99
* fix snap deploy stage (3064) casperdcl
* dvc: update gc to remove unpacked dir (3054) sharidas
* test: merge _should_test_aws and _get_aws_url inside S3 test helper (3073) skshetry
* test: merge _should_test_oss and _get_oss_url inside OSS test helper (3071) skshetry
* http/ imp tests - migrate do dir helpers (3070) pared
* dependency: test: migrate to dir helpers (3068) pared
* cache: test: migrate to dir helpers (3067) pared
* analytics: tests: migrate to dir helpers (3066) pared
* tests: api: convert to dir helpers (3044) pared
* Snap classic deployment (3063) casperdcl
* completion: fix --relink problem (3061) mroutis
* local-related methods should verify that WorkingTree is in use (3018) pared
* tests: remote: local: migrate to dir fixtures (3049) pared
* import: allow importing from non-DVC git repositories (3020) chatcannon
* test: Merge _should_test_azure and _get_azure_url inside Azure test helper (3055) skshetry
* test: add _should_test_gdrive and _get_gdrive_url inside GDrive (3056) skshetry
* py3: use yield from where appropriate (3052) Suor
* test: do not bootstrap repo template and version files in erepo_dir (3045) Suor
* dvc: optimize and clean up stages collection (3048) Suor
* dvc: autowrap repo tree into CleanTree (3047) Suor
* test: add TmpDir.chdir() (3043) Suor
* dvc: clean brancher (3046) Suor
* py3: refactor exceptions (3042) mroutis
* py3: use new magic from PEP 3135 (3039) mroutis
* Restyle fix for base None value (3041) restyled-io
* Ensure `relpath` accepts str and Path-like objects (3037) algomaster99
* metrics: don't show working tree if it is clean (3025) Suor
* ui: add checkout --relink to autocomplete scripts (3026) Suor
* py3: migrate utils/compat.py to compat.py (3032) mroutis
* py3: remove imports from utils.compat (3031) mroutis
* py3: remove csv_reader and makedirs from utils/compat.py (3030) mroutis
* py3: remove methods for casting bytes in python 2 (3029) mroutis

* py3: remove string compat related code (3024) mroutis
* py3: get rid of is_py checks (3021) mroutis
* py3: remove future imports (3022) mroutis
* py3: deprecate 2.7 (3019) mroutis
* tests: func: convert test_get.py test_utils.py to new fixtures (3014) efiop
* repo: move dvcignore from repo to tree (2974) pared
* dvc: make graph consist of stages not their paths (3012) Suor
* dvc: support granularity for fetch/pull/push/status/checkout (3002) efiop
* Improve Google Drive auth failure error reporting (2991) MaxRis
* summon: first draft with python specific implementation (2971) mroutis
* ui: fix extra newline in dvc version (3006) Suor
* test: test ignore nuances (3003) Suor

Fix `inflect` version.

* dvc: use ' to mark dynamic command output, et al. (2986) jorgeorpinel
* tests: use dir_helpers on repo (2950) mroutis
* tests: use dir helpers on updater (2952) mroutis
* import: test: refactor to dir helpers (2935) pared
* ui: reorder checkout options to go from common to rare (2966) Suor
* remote: s3: adjust jobs number basing on file descriptors number (2866) pared
* import: allow downloading regular files/dirs tracked by git (2889) Baranowski
* Standardize gdrive tests with others remotes (2958) MaxRis
* temporary_windows_drive fixture: move to dir_helpers (2937) pared
* tests: use dir helpers on analytics (2951) mroutis

* Restyle remote: use absolute from root for gdrive credentials file (2949) e3bo