Update to 0.54.0

Changelog:
Enhancements
Templates

    Adjust tests ddc6d4e3 @bep #5643
    Prevent getJSON and getCSV fetch failure from aborting build 6a2bfcbe @anthonyfok #5643

Core

    Expand TestPageWithEmoji to cover '+', '-' and '_' too 2a9060a8 @anthonyfok #5635
    Restore 0.48 slash handling in taxonomies 40ffb048 @bep #5571

Other

    Use official semver even for main releases fab41f42 @bep #5639
    Add test for --configDir 59d87044 @bep #5662
    Ignore unknown config files in config dir 3244cb3b @bep #5646
    Store supported config formats in a variable d9282cf9 @tryzniak
    Bump to Go 1.11.5 8ed2a1ca @bep #5654
    Update Afero e8596139 @bep #5650
    Accept hyphen and plus sign in emoji detection 3038464e @anthonyfok #5635
    Support numeric sort in ByParam 26f75edb @tryzniak #5305
    Make hugo server -t work again db3c49d0 @tryzniak #5569#5061#4868
    Add configFile(s) back to the watch list after RENAME event too e3cb8e6c @anthonyfok #5205
    Remove historical rssURI config 55251aa8 @mywaiting
    Use subtests with server_test.go 843fcd19 @tryzniak
    Move resource interfaces into its own package ce8a09a4 @bep
    Move resource processors into sub-packages 669ada43 @bep
    Update _index.md 50745122 @vrMarc
    Update go.sum 0584432b @bep
    Update Chroma cc351958 @bep #4993
    Make docshelper run again c24f3ae2 @bep #5568

Fixes
Templates

    Fix reflect 9e4f9e0b @moorereason #5564

Other

    Fix some inline shortcode issues c52045bb @bep #5645#5653
    Fix OpenGraph image fallback to site params 526b5b1c @statik
    Fix Params case handling in the new site global e1a66c73 @bep #5615
    cache/namedmemcache: Fix data race 3f3187de @bep

(ryoon)