Turrets never stopped spinning up. Fix this.

Broken in commit c4d60b8503894766fdb20b80ae6717b020421a4a.
Don't create renderbuffers that aren't used anyway.
add gfx_shader_mod for managing dynamic shaders

when called :act it will replace "shader"-shader with "replacement"-shader
on :reset it will replace it back to "shader"-shader
Add a r_heatHaze cvar with default 0
Add menu options for heat haze
Add Heat Haze on for highest, and off for all other graphic presets
librendererGL: prevent ‘missing image’ for shaders without diffuse or colour stages.

This is done via a new keyword, “implicitMapGL1”. librendererGL treats as if
it were implicitMap; librendererGL3 parses but otherwise ignores it.
Bump version nos.
Fix bashisms in tarball.sh.
update client en.po, templates, as well as game .po files
updating french game translation
Merge branch 'master' into librocket

Conflicts:
	main/ui/ingame_options.menu
	main/ui/options.menu