Ohmmeter and Triangular Voltage Symbols

Dear Massimo Redaelli,

some minutes ago, I wrote you an eMail concering some symbols I miss in circuitikz... then I realized that you have a git repository and forked your work for some minor modifications. I added two new symbols, a Triangular Voltage Symbol (based on the Square Voltage Symbol) and an Ohmmeter, similar to the Ampère- and Voltmeter you already had in your package. I chose to add these two symbols because
* they are universal, used in (as far as I know) every language
* they match the style of already existing symbols and extend the range in a logical way

I would like / can add other symbols as well, but I wanted to hear your opinion, because it is your package and I do not want to "ruin" your work ;)

Greetings from Karlsruhe, Germany,

Ralf Farkas

![demo](https://f.cloud.github.com/assets/898513/185097/ad20c71e-7cfa-11e2-8e81-cae1a55dfc11.png)