update elements and fix some bugs

lib/src/prism/components/prism-fsharp.js

 Prism.languages.fsharp = Prism.languages.extend('clike', {
         'comment': [
                 {
                         pattern: /(^|[^\\])\(\*[\w\W]*?\*\)/,
                         lookbehind: true
                 },
                 {
                         pattern: /(^|[^\\:])\/\/.*/,
                         lookbehind: true
                 }
         ],
-        'keyword': /\b(abstract|and|as|assert|base|begin|class|default|delegate|do|done|downcast|downto|elif|else|end|exception|extern|false|finally|for|fun|function|global|if|in|inherit|inline|interface|internal|lazy|let|let!|match|member|module|mutable|namespace|new|not|null|of|open|or|override|private|public|rec|return|return!|select|static|struct|then|to|true|try|type|upcast|use|use!|val|void|when|while|with|yield|yield!|asr|land|lor|lsl|lsr|lxor|mod|sig|atomic|break|checked|component|const|constraint|constructor|continue|eager|event|external|fixed|functor|include|method|mixin|object|parallel|process|protected|pure|sealed|tailcall|trait|virtual|volatile)\b/,
-        'string': /@?("""|"|')((\\|\n)?.)*?\1B?/,
-        'preprocessor': /^\s*#.*/m,
+        'keyword': /\b(?:let|return|use|yield)(?:!\B|\b)|\b(abstract|and|as|assert|base|begin|class|default|delegate|do|done|downcast|downto|elif|else|end|exception|extern|false|finally|for|fun|function|global|if|in|inherit|inline|interface|internal|lazy|match|member|module|mutable|namespace|new|not|null|of|open|or|override|private|public|rec|select|static|struct|then|to|true|try|type|upcast|val|void|when|while|with|asr|land|lor|lsl|lsr|lxor|mod|sig|atomic|break|checked|component|const|constraint|constructor|continue|eager|event|external|fixed|functor|include|method|mixin|object|parallel|process|protected|pure|sealed|tailcall|trait|virtual|volatile)\b/,
+        'string': /(?:"""[\s\S]*?"""|@"(?:""|[^"])*"|("|')(?:\\\1|\\?(?!\1)[\s\S])*\1)B?/,
         'number': [
                 /\b-?0x[\da-fA-F]+(un|lf|LF)?\b/,
                 /\b-?0b[01]+(y|uy)?\b/,
-                /\b-?(\d+\.|\d*\.?\d+)([fFmM]|[eE][+-]?\d+)?\b/,
+                /\b-?(\d*\.?\d+|\d+\.)([fFmM]|[eE][+-]?\d+)?\b/,
                 /\b-?\d+(y|uy|s|us|l|u|ul|L|UL|I)?\b/
         ]
+});
+Prism.languages.insertBefore('fsharp', 'keyword', {
+        'preprocessor': /^[^\r\n\S]*#.*/m
 });