using wildcard in l3build instead of hardcoded filename

Author: samcarter

Diff for: .gitignore

@@ -7,3 +7,4 @@ icon.png
 !doc/examples/a-lecture/beamerexample-lecture-logo.pdf
 
 doc/.latexmkrc
+.latexmkrc

Diff for: build.lua

@@ -12,7 +12,7 @@ sourcefiledir = "./base"
 flattentds = false
 
 -- Install all files from the source tree directly
-installfiles = {"**/*.cls", "**/*.sty", "**/beamericon*.*", "**/beamerbasenavigationsymbols.tex"}
+installfiles = {"**/*.cls", "**/*.sty", "**/beamericon*.*", "**/*.tex"}
 sourcefiles  = installfiles
 unpackfiles  = { }