Filter out warnings when autocompleting commands.

When autocompleting accounts or payees in the command line, one may get
warnings, for instance when the source file has checks like the
following:

tag CSV
    check tag('CSV') =~ /PAYPAL/ ? \
    (has_tag('via') && (tag('via') =~ /PayPal/)) || (payee =~ /PayPal/) : 1

Note that Ledger may emit warnings even when --strict is not passed.
So g:ledger_extra_options (see earlier commits) does not fix completion
issues completely. This commit addresses the problem by filtering out
lines that start with `Warning: `. This works as long as warning
messages are one line messages (and the user does have top level
accounts called `Warning: `!).

Author: Lifepillar

ftplugin/ledger.vim

@@ -411,10 +411,10 @@ endf "}}}
 function! s:autocomplete_account_or_payee(argLead, cmdLine, cursorPos) "{{{2
   return (a:argLead =~ '^@') ?
         \ map(filter(systemlist(g:ledger_bin . ' -f ' . shellescape(expand(g:ledger_main)) . ' payees'),
-        \ "v:val =~? '" . strpart(a:argLead, 1) . "'"), '"@" . escape(v:val, " ")')
+        \ "v:val =~? '" . strpart(a:argLead, 1) . "' && v:val !~? '^Warning: '"), '"@" . escape(v:val, " ")')
         \ :
         \ map(filter(systemlist(g:ledger_bin . ' -f ' . shellescape(expand(g:ledger_main)) . ' accounts'),
-        \ "v:val =~? '" . a:argLead . "'"), 'escape(v:val, " ")')
+        \ "v:val =~? '" . a:argLead . "' && v:val !~? '^Warning: '"), 'escape(v:val, " ")')
 endf "}}}
 
 function! s:reconcile(account) "{{{2