* WorkingFiles::files : vector -> unordered_map
* Add timestamp to WorkingFile
* Rename "comp-preload" thread to "preamble"
* Rename CompletionManager to SemaManager as it is used by "diag" "comp" "preamble"
* Rename clang_complete.* to sema_manager.*
* Merge SemaManager::{preloads,sessions}
* Add initialization option session.maxNum
* In DiagnosticMain, if an included file was modified, cancel the DiagTask and create a PreambleTask instead. The task sets `from_diag` so as to trigger immediate DiagTask after the preamble is built.
Delete method.{cc,h}
Rename $ccls/setSkippedRanges to $ccls/publishSkippedRanges
Rename $ccls/publishSemanticHighlighting to $ccls/publishSemanticHighlight; stableId -> id
blacklist some undesired candidates
additionalTextEdits if clang>=7
Use CodePatterns for preprocessor directive completion if there is a #
Prefer textEdit over insertText
Move using below #include to make preamble happy
textDocument/references: if no references, first line or last line => list where this file is included
malloc_trim() only if files have been indexed in last cycle
Intern: use CachedHashStringRef
