changed <svg> tag regexes

[LordPachelbel]

To solve issue #19, these regex changes (based on https://github.com/tiagoporto/jquery-svg-to-inline/issues/19#issuecomment-407540570 ) allow for inlining SVG files with

• underscores in the <svg> tag — <svg id="Layer_1"
• semicolons in the <svg> tag — <svg style="enable-background:new 0 0 512 512;"
• no attributes or whitespace in the tag — <svg>

The regexes are now less restrictive, so they should cover any situation. The <svg> one says "match <svg, then match anything that isn't a > character, then match a > character." While I was at it, I changed the regexes that find HTML comments, the <?xml tag, and the class attribute in the same manner.

This is the SVG I used for testing (I had to change its extension to .txt so I could attach it to this pull request, so change it back to .svg before using it):

calculator.txt

[LordPachelbel]

After submitting this pull request the Travis CI build failed at the npm ci step, so it hasn't checked my code.

[tiagoporto]

Hi @LordPachelbel its not a problem with your code, I need update some dependencies now.
Thanks for your contribution.