CMakeLists.txt: Allow users to override the CMAKE_INSTALL_PREFIX

Check whether CMAKE_INSTALL_PREFIX is defined before overwriting
its value.  This allows users to specify an alternate install prefix
during the `cmake` invocation.

Signed-off-by: David Aguilar <davvid@gmail.com>
Merge pull request #4 from davvid/install-prefix

CMakeLists.txt: Allow users to override the CMAKE_INSTALL_PREFIX
CMakeLists.txt: Fix cmake warning

IF(...) statements must end with equivalent ENDIF(...) statements.

Signed-off-by: David Aguilar <davvid@gmail.com>
Merge pull request #5 from davvid/install-prefix

CMakeLists.txt: Fix cmake warning
.gitignore: Add entry for src/SeExpr/generated
SeExprBuildins.cpp: Avoid ambiguous operator overloading

i686-apple-darwin11-llvm-g++-4.2 (GCC) 4.2.1
(Based on Apple Inc. build 5658) (LLVM build 2336.9.00)
from Mac OS X Lion, and possibly others, fail to build
due to expressions that contain ambiguous overloaded operators.

	.../src/SeExpr/SeExprBuiltins.cpp:596:28:
	      error: use of overloaded operator '+' is ambiguous
	      (with operand types 'SeVec3d' and 'double')
	return .5*vnoise(p)+.5;
	       ~~~~~~~~~~~~^~~

	.../src/SeExpr/SeExprBuiltins.cpp:857:65:
	      error: use of overloaded operator '-' is ambiguous
	      (with operand types 'SeVec3d' and 'double')
	...data.points[n] = testcell + jitter * (ccellnoise(testcell - .5));
	                                                    ~~~~~~~~ ^ ~~
Use SeVec3d(double) in these expressions to avoid ambiguities.
cmake: Allow specifying the library directory

Add a CMAKE_INSTALL_LIBDIR variable to allow packagers
to specify the library directory name.

The default is "lib64", but some systems use "lib", so
allow users to specify the basename.
Merge pull request #6 from davvid/lion

Lion
Update the shadeop for new renderman versions and update fit's help
Fix memory leaks in SeExpr (now valgrind clean except for dlopen/sym stuff)

Fucnctions instance is now no longer mallocd()
Store all strings made by the lexer in an array that have lifetime
  contingent on SeExprFunc. This avoids memory leaks on parse errors.
  It also allows us to not copy strings in SeExprAssignNode and
  SeExprVarNode
Also dlclose() at destruction of FuncTable time
Merge pull request #8 from aselle/master

Memory leak pass
Fixing pedantic warnings
Merge pull request #9 from aselle/master

Warning fix
Windows compiler fix
More windows compile fixes... (allow not having qt and not having doxygen)
One more fix (remove required argument from Qt search)
More windows fixes (this time to the Segraph demo)
Merge branch 'wdas-master' into  redpawfx/master