Fix weak symbol linkage in shared objects

Weak symbols must be called indirectly (la+jalr), not via PLT (auipc+jalr).
correctly relocate vf targets
Correct and improve {get/make/set}context routines
change README to markdown
Fix problems building documentation with newer versions of makeinfo.

Someone decided that makeinfo should parse commands inside
comments. This fix may seem incorrect, but it's the "official" one.
http://www.mail-archive.com/bug-binutils@gnu.org/msg14429.html
Fix problems building documentation with newer versions of makeinfo (part 2).

Add more documentation organization fixes. These should have been
included in the prior commit - 23a86816bd960be84bd908cfb3a8099650252e72
http://www.mail-archive.com/bug-binutils@gnu.org/msg14429.html
Fix problems building documentation with newer versions of makeinfo (part 3).

Add more documentation organization fixes. These should have been
included in the prior commits.
More fixes for newer versions of texinfo
Add division emulation code

Measurement indicates that this is code is reasonably performant while
respecting code size.
Fix names of frame-related funcs/structs

These don't match MIPS at all anymore.