Add statusline and tabline component functions

[lambdalisue]

Now following component functions are available

• gin#component#branch#ascii()
• gin#component#branch#unicode()
• gin#component#traffic#ascii()
• gin#component#traffic#unicode()
• gin#component#worktree#full()
• gin#component#worktree#name()

Use those like

set statusline+=\ %{gin#component#worktree#name()}
set statusline+=\ (%{gin#component#branch#unicode()})
set statusline+=\ [%{gin#component#traffic#unicode()}]

Or with lightline.vim

let g:lightline = {
	\ 'colorscheme': 'wombat',
	\ 'active': {
	\   'left': [['mode', 'paste'], ['gitbranch']],
	\ },
	\ 'component_function': {
	\   'gitbranch': 'gin#component#branch#unicode',
	\ },
	\}