More Handlebars helpers

[bubblobill]

Identify the Bug or Feature request

progresses #4158

Description of the Change

added handlebars helpers.
added template cache.

• New class HandlebarsHelpers to contain helpers.
• Helper registration moved to HandlebarsHelpers.

LibraryTemplateLoader class changes:

Normally it is not noticable, but on consecutive nested calls (i.e. calls to templates inside a template, as used in the include helper), Windows paths break the URL lookup, .e.g. when the first character is checked for / but it is a \.

New helper list;

previously existing helpers

• StringHelpers:
  • capitalizeFirst,
  • center,
  • cut,
  • defaultIfEmpty,
  • join,
  • ljust,
  • rjust,
  • substring,
  • lower,
  • upper,
  • slugify,
  • stringFormat,
  • stripTags,
  • capitalize,
  • abbreviate,
  • wordWrap,
  • replace,
  • yesno,
  • dateFormat,
  • numberFormat
• ConditionalHelpers:
  • eq,
  • neq,
  • gt,
  • gte,
  • lt,
  • lte,
  • and,
  • or,
  • not
• NumberHelpers:
  • isEven
  • isOdd
  • stripes
• AssignHelper:
  • assign
• IncludeHelper:
  • include
• Base64EncodeHelper
  • base64Encode

new helpers

• Jackson2Helper:
  • json
• MarkdownHelper:
  • markdown
• MathsHelpers:
  • add,
  • subtract,
  • multiply,
  • divide,
  • max,
  • min,
  • mod,
  • div,
  • pow,
  • abs,
  • sqrt,
  • tau,
  • pi

Possible Drawbacks

things don't work as I think they should

Documentation Notes

added handlebars helpers.

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