Wrapping math and macros

[pitkling]

After the Atom latextools package seems abandoned, I found the latexer package together with the latex package a more than apt replacement. A few things than are missing and that seem like a nice feature addition to latexer:

• math wrapping: when selecting some text and hitting '$', the selected text should be surrounded by '$'
• macro wrapping: when selecting some text there should be a shortcut to generate a macro that takes this text as an argument (so selecting 'foo' and hitting the shortcut would result in '\{foo}' with the cursor immediately after the '\', so that one can just enter the macro name
• specific-macro wrapping: shortcuts for some standard macro wrappers (e,g., emph)
• environment wrapping: a similar feature to wrap selected text in an environment