Tikz支持上线

配置了基于`tikzjax`的tikz渲染。目前只支持最基本的tikz，不支持circuitikz等。 ```tikz \begin{tikzpicture}[scale=2] \draw[help lines,step=.3] (0,-1.1) grid (2*pi+.1,1.1); \draw[->,thick] (-2.7,0) -- (2*pi+.2,0) node[anchor=north] {$x$}; \draw[->,thick] (0,-1.2) -- (0,1.2) node[anchor=east] {$y$}; \draw (-.05, 1) -- (.05, 1) node[anchor=east] at(0, 1) {$1$}; \draw (-.05,-1) -- (.05,-1) node[anchor=east] at(0,-1) {$-1$}; \foreach \x/\y in {0.5/\frac{1}{2},1/,1.5/\frac{3}{2},2/2} \draw (\x*pi,-.05) -- (\x*pi,.05) node at(\x*pi,-.2) {$\y\pi$}; \draw[thick] (-1.5,0) circle[radius=1]; \filldraw[draw=green!50!black,fill=green!50!white] (-1.5,0) -- +(.3,0) arc [start angle=0,end angle=30,radius=.3] -- cycle; \path (-1.5,0) ++ (15:.5) node[color=green!80!black] {$30^\circ$}; \draw[thick] (-1.5,0) -- +(30:1) -- (pi/6,.5); \draw[thick,dashed] (pi/6,.5) -- (pi/6,0); \node at (pi/6,-.2) {$\frac{1}{6}\pi$}; \draw[samples=50,domain=0:2*pi,very thick,color=red!70!white] plot(\x,{sin(\x r)}); \end{tikzpicture} ```