Use SVG LaMa icon instead of PNG

Because PNG is not scalable and looks ugly.
The actual SVG was generated using https://viereck.ch/latex-to-svg/ from
the following LaTeX code:

\lambda\kern -.1667em\lower -.5ex\hbox{$a$}\kern -.1000em\lower .2ex\hbox{$\mathcal M$}\kern -.1000em\lower -.5ex\hbox{$a$}

Signed-off-by: Kakadu <[email protected]>

README.md

@@ -7,11 +7,9 @@
 [3]:  https://github.com/JetBrains-Research/Lama-devel/workflows/Build/badge.svg?branch=1.10
 [4]:  https://github.com/JetBrains-Research/Lama-devel/actions
 
-
-
 # Lama
 
-![lama](lama.png) is a programming language developed by JetBrains Research for educational purposes as an exemplary language to introduce
+![lama](lama.svg) is a programming language developed by JetBrains Research for educational purposes as an exemplary language to introduce
 the domain of programming languages, compilers and tools. Its general characteristics are:
 
 * procedural with first-class functions - functions can be passed as arguments, placed in data structures,
@@ -24,11 +22,11 @@ the domain of programming languages, compilers and tools. Its general characteri
 * with user-defined infix operators, including those defined in local scopes;
 * with automatic memory management (garbage collection).
 
-The name ![lama](lama.png) is an acronym for *Lambda-Algol* since the language has borrowed the syntactic shape of
+The name ![lama](lama.svg) is an acronym for *Lambda-Algol* since the language has borrowed the syntactic shape of
 operators from **Algol-68**; [**Haskell**](http://www.haskell.org) and [**OCaml**](http://ocaml.org) can be
 mentioned as other languages of inspiration.
 
-The main purpose of ![lama](lama.png) is to present a repertoire of constructs with certain runtime behavior and
+The main purpose of ![lama](lama.svg) is to present a repertoire of constructs with certain runtime behavior and
 relevant implementation techniques. The lack of a type system (a vital feature for a real-word language
 for software engineering) is an intensional decision which allows to show the unchained diversity
 of runtime behaviors, including those which a typical type system is called to prevent. On the other hand
@@ -37,7 +35,7 @@ type systems) on.
 
 The current implementation contains a native code compiler for **x86-32**, written
 in **OCaml**, a runtime library with garbage-collection support, written in **C**, and a small
-standard library, written in ![lama](lama.png) itself. The native code compiler uses **gcc** as a toolchain.
+standard library, written in ![lama](lama.svg) itself. The native code compiler uses **gcc** as a toolchain.
 
 In addition, a source-level reference interpreter is implemented as well as a compiler to a small
 stack machine. The stack machine code can in turn be either interpreted on a stack machine interpreter, or
@@ -54,11 +52,11 @@ Windows users should get Windows Subsystem for Linux a.k.a WSL (recommended) or
 * System-wide prerequisites:
 
   - `sudo apt install gcc-multilib` (in Debian-based GNU/Linux)
-   
-     On some versions you need to install additional package `lib32gcc-9-dev` in case of errors like 
-       ```       
+
+     On some versions you need to install additional package `lib32gcc-9-dev` in case of errors like
+       ```
       /usr/bin/ld: cannot find -lgcc
-      /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/9/libgcc.a when searching for -lgcc              
+      /usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/9/libgcc.a when searching for -lgcc
        ```
   - [opam](http://opam.ocaml.org) (>= 2.0.4)
   - [OCaml](http://ocaml.org) (>= 4.10.1). *Optional* because it can be easily installed through opam. Compiler variant with `flambda` switch is recommended