multiple changes for nvim

- tex snippets were changed for listed and unlisted sections
- nvim autocompletion engine was swapped to nvim-cmp
- nvim clears more files when exiting tex files
- the compiler uses biber when compiling tex files
- sc-im is used for .sc filetypes when using vifm

.config/nvim/UltiSnips/tex.snippets

@@ -91,37 +91,37 @@ snippet ,sc "Small caps" A
 endsnippet
 
 snippet ,chap "Chapter" A
-\chapter {$1}
+\chapter{$1}
+$2
+endsnippet
+
+snippet ,usec "Section" A
+\section{$1}
 $2
 endsnippet
 
 snippet ,sec "Section" A
-\section* {$1}
-$2
-endsnippet
-
-snippet ,lsec "Section" A
-\section {$1}
+\section{$1}
 $2
 endsnippet
 
 snippet ,ssec "Subsection" A
-\subsection* {$1}
+\subsection{$1}
 $2
 endsnippet
 
 snippet ,sssec "Subsubsection" A
-\subsubsection* {$1}
+\subsubsection{$1}
 $2
 endsnippet
 
 snippet ,par "Paragraph" A
-\paragraph* {$1}
+\paragraph{$1}
 $2
 endsnippet
 
 snippet ,spar "Subparagraph" A
-\subparagraph* {$1}
+\subparagraph{$1}
 $2
 endsnippet